diff --git a/engine/src/flutter/ci/analyze.sh b/engine/src/flutter/ci/analyze.sh
index 536d9332898..6eb2a529c94 100755
--- a/engine/src/flutter/ci/analyze.sh
+++ b/engine/src/flutter/ci/analyze.sh
@@ -1,81 +1,94 @@
 #!/bin/bash
+#
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+set -e
+
+# Needed because if it is set, cd may print the path it changed to.
+unset CDPATH
+
+# On Mac OS, readlink -f doesn't work, so follow_links traverses the path one
+# link at a time, and then cds into the link destination and find out where it
+# ends up.
+#
+# The function is enclosed in a subshell to avoid changing the working directory
+# of the caller.
+function follow_links() (
+  cd -P "$(dirname -- "$1")"
+  file="$PWD/$(basename -- "$1")"
+  while [[ -L "$file" ]]; do
+    cd -P "$(dirname -- "$file")"
+    file="$(readlink -- "$file")"
+    cd -P "$(dirname -- "$file")"
+    file="$PWD/$(basename -- "$file")"
+  done
+  echo "$file"
+)
+
+SCRIPT_DIR=$(follow_links "$(dirname -- "${BASH_SOURCE[0]}")")
+SRC_DIR="$(cd "$SCRIPT_DIR/../.."; pwd -P)"
+FLUTTER_DIR="$SRC_DIR/flutter"
+DART_BIN="$SRC_DIR/third_party/dart/tools/sdks/dart-sdk/bin"
+PUB="$DART_BIN/pub"
+DART_ANALYZER="$DART_BIN/dartanalyzer"
+
+echo "Using analyzer from $DART_ANALYZER"
+
+"$DART_ANALYZER" --version
+
+function analyze() (
+  local last_arg="${!#}"
+  local results
+  # Grep sets its return status to non-zero if it doesn't find what it's
+  # looking for.
+  set +e
+  results="$("$DART_ANALYZER" "$@" 2>&1 |
+    grep -Ev "No issues found!" |
+    grep -Ev "Analyzing.+$last_arg")"
+  set -e
+  echo "$results"
+  if [ -n "$results" ]; then
+    echo "Failed analysis of $last_arg"
+    return 1
+  else
+    echo "Success: no issues found in $last_arg"
+  fi
+  return 0
+)
+
 echo "Analyzing dart:ui library..."
-
-echo "Using analyzer from `which dartanalyzer`"
-
-dartanalyzer --version
-
-RESULTS=`dartanalyzer                                                          \
-  --options flutter/analysis_options.yaml                                      \
-  --enable-experiment=non-nullable                                             \
-  "$1out/host_debug_unopt/gen/sky/bindings/dart_ui/ui.dart"                    \
-  2>&1                                                                         \
-  | grep -Ev "No issues found!"                                                \
-  | grep -Ev "Analyzing.+out/host_debug_unopt/gen/sky/bindings/dart_ui/ui\.dart"`
-
-echo "$RESULTS"
-if [ -n "$RESULTS" ]; then
-  echo "Failed."
-  exit 1;
-fi
+analyze \
+  --options "$FLUTTER_DIR/analysis_options.yaml" \
+  --enable-experiment=non-nullable \
+  "$SRC_DIR/out/host_debug_unopt/gen/sky/bindings/dart_ui/ui.dart"
 
 echo "Analyzing flutter_frontend_server..."
-RESULTS=`dartanalyzer                                                          \
-  --packages=flutter/flutter_frontend_server/.dart_tool/package_config.json    \
-  --options flutter/analysis_options.yaml                                      \
-  flutter/flutter_frontend_server                                              \
-  2>&1                                                                         \
-  | grep -Ev "No issues found!"                                                \
-  | grep -Ev "Analyzing.+frontend_server"`
-echo "$RESULTS"
-if [ -n "$RESULTS" ]; then
-  echo "Failed."
-  exit 1;
-fi
+analyze \
+  --packages="$FLUTTER_DIR/flutter_frontend_server/.dart_tool/package_config.json" \
+  --options "$FLUTTER_DIR/analysis_options.yaml" \
+  "$FLUTTER_DIR/flutter_frontend_server"
 
 echo "Analyzing tools/licenses..."
-(cd flutter/tools/licenses && pub get)
-RESULTS=`dartanalyzer                                                          \
-  --packages=flutter/tools/licenses/.dart_tool/package_config.json             \
-  --options flutter/tools/licenses/analysis_options.yaml                       \
-  flutter/tools/licenses                                                       \
-  2>&1                                                                         \
-  | grep -Ev "No issues found!"                                                \
-  | grep -Ev "Analyzing.+tools/licenses"`
-echo "$RESULTS"
-if [ -n "$RESULTS" ]; then
-  echo "Failed."
-  exit 1;
-fi
+(cd "$FLUTTER_DIR/tools/licenses" && "$PUB" get)
+analyze \
+  --packages="$FLUTTER_DIR/tools/licenses/.dart_tool/package_config.json" \
+  --options "$FLUTTER_DIR/tools/licenses/analysis_options.yaml" \
+  "$FLUTTER_DIR/tools/licenses"
 
 echo "Analyzing testing/dart..."
-flutter/tools/gn --unoptimized
-ninja -C out/host_debug_unopt sky_engine sky_services
-(cd flutter/testing/dart && pub get)
-RESULTS=`dartanalyzer                                                          \
-  --packages=flutter/testing/dart/.dart_tool/package_config.json               \
-  --options flutter/analysis_options.yaml                                      \
-  flutter/testing/dart                                                         \
-  2>&1                                                                         \
-  | grep -Ev "No issues found!"                                                \
-  | grep -Ev "Analyzing.+testing/dart"`
-echo "$RESULTS"
-if [ -n "$RESULTS" ]; then
-  echo "Failed."
-  exit 1;
-fi
+"$FLUTTER_DIR/tools/gn" --unoptimized
+ninja -C "$SRC_DIR/out/host_debug_unopt" sky_engine sky_services
+(cd "$FLUTTER_DIR/testing/dart" && "$PUB" get)
+analyze \
+  --packages="$FLUTTER_DIR/testing/dart/.dart_tool/package_config.json" \
+  --options "$FLUTTER_DIR/analysis_options.yaml" \
+  "$FLUTTER_DIR/testing/dart"
 
 echo "Analyzing testing/scenario_app..."
-(cd flutter/testing/scenario_app && pub get)
-RESULTS=`dartanalyzer                                                          \
-  --packages=flutter/testing/scenario_app/.dart_tool/package_config.json       \
-  --options flutter/analysis_options.yaml                                      \
-  flutter/testing/scenario_app                                                 \
-  2>&1                                                                         \
-  | grep -Ev "No issues found!"                                                \
-  | grep -Ev "Analyzing.+testing/scenario_app"`
-echo "$RESULTS"
-if [ -n "$RESULTS" ]; then
-  echo "Failed."
-  exit 1;
-fi
\ No newline at end of file
+(cd "$FLUTTER_DIR/testing/scenario_app" && "$PUB" get)
+analyze \
+  --packages="$FLUTTER_DIR/testing/scenario_app/.dart_tool/package_config.json" \
+  --options "$FLUTTER_DIR/analysis_options.yaml" \
+  "$FLUTTER_DIR/testing/scenario_app"
diff --git a/engine/src/flutter/ci/bin/lint.dart b/engine/src/flutter/ci/bin/lint.dart
index c573ab578c1..04ff295acd5 100644
--- a/engine/src/flutter/ci/bin/lint.dart
+++ b/engine/src/flutter/ci/bin/lint.dart
@@ -1,9 +1,13 @@
-/// Runs clang-tidy on files with changes.
-///
-/// usage:
-/// dart lint.dart <path to compile_commands.json> <path to git repository> [clang-tidy checks]
-///
-/// User environment variable FLUTTER_LINT_ALL to run on all files.
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Runs clang-tidy on files with changes.
+//
+// usage:
+// dart lint.dart <path to compile_commands.json> <path to git repository> [clang-tidy checks]
+//
+// User environment variable FLUTTER_LINT_ALL to run on all files.
 
 import 'dart:async' show Completer;
 import 'dart:convert' show jsonDecode, utf8, LineSplitter;
diff --git a/engine/src/flutter/ci/build.sh b/engine/src/flutter/ci/build.sh
index 6e63dd9c9fd..5555fc4efd5 100755
--- a/engine/src/flutter/ci/build.sh
+++ b/engine/src/flutter/ci/build.sh
@@ -1,21 +1,50 @@
 #!/bin/bash
-set -ex
+#
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
 
-PATH="$HOME/depot_tools:$PATH"
-cd ..
+set -e
 
-PATH=$(pwd)/third_party/dart/tools/sdks/dart-sdk/bin:$PATH
+# Needed because if it is set, cd may print the path it changed to.
+unset CDPATH
+
+# On Mac OS, readlink -f doesn't work, so follow_links traverses the path one
+# link at a time, and then cds into the link destination and find out where it
+# ends up.
+#
+# The function is enclosed in a subshell to avoid changing the working directory
+# of the caller.
+function follow_links() (
+  cd -P "$(dirname -- "$1")"
+  file="$PWD/$(basename -- "$1")"
+  while [[ -h "$file" ]]; do
+    cd -P "$(dirname -- "$file")"
+    file="$(readlink -- "$file")"
+    cd -P "$(dirname -- "$file")"
+    file="$PWD/$(basename -- "$file")"
+  done
+  echo "$file"
+)
+
+SCRIPT_DIR=$(follow_links "$(dirname -- "${BASH_SOURCE[0]}")")
+SRC_DIR="$(cd "$SCRIPT_DIR/../.."; pwd -P)"
+FLUTTER_DIR="$SRC_DIR/flutter"
+
+set -x
+
+PATH="$SRC_DIR/third_party/dart/tools/sdks/dart-sdk/bin:$HOME/depot_tools:$PATH"
+
+cd "$SRC_DIR"
 
 # Build the dart UI files
-flutter/tools/gn --unoptimized
-ninja -C out/host_debug_unopt generate_dart_ui
+"$FLUTTER_DIR/tools/gn" --unoptimized
+ninja -C "$SRC_DIR/out/host_debug_unopt" generate_dart_ui
 
 # Analyze the dart UI
-flutter/ci/analyze.sh
-flutter/ci/licenses.sh
+"$FLUTTER_DIR/ci/analyze.sh"
+"$FLUTTER_DIR/ci/licenses.sh"
 
 # Check that dart libraries conform
-cd flutter/web_sdk
-pub get
-cd ..
-dart web_sdk/test/api_conform_test.dart
+(cd "$FLUTTER_DIR/web_sdk"; pub get)
+(cd "$FLUTTER_DIR"; dart "web_sdk/test/api_conform_test.dart")
\ No newline at end of file
diff --git a/engine/src/flutter/ci/check_gn_format.py b/engine/src/flutter/ci/check_gn_format.py
index 2257a58984d..8867849cd2d 100755
--- a/engine/src/flutter/ci/check_gn_format.py
+++ b/engine/src/flutter/ci/check_gn_format.py
@@ -8,8 +8,6 @@ import sys
 import subprocess
 import os
 import argparse
-import errno
-import shutil
 
 def GetGNFiles(directory):
   directory = os.path.abspath(directory)
diff --git a/engine/src/flutter/ci/check_roll.sh b/engine/src/flutter/ci/check_roll.sh
index 296300d3eae..ffb2cca9728 100755
--- a/engine/src/flutter/ci/check_roll.sh
+++ b/engine/src/flutter/ci/check_roll.sh
@@ -1,4 +1,36 @@
 #!/bin/bash
+#
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+set -e
+
+# Needed because if it is set, cd may print the path it changed to.
+unset CDPATH
+
+# On Mac OS, readlink -f doesn't work, so follow_links traverses the path one
+# link at a time, and then cds into the link destination and find out where it
+# ends up.
+#
+# The function is enclosed in a subshell to avoid changing the working directory
+# of the caller.
+function follow_links() (
+  cd -P "$(dirname -- "$1")"
+  file="$PWD/$(basename -- "$1")"
+  while [[ -h "$file" ]]; do
+    cd -P "$(dirname -- "$file")"
+    file="$(readlink -- "$file")"
+    cd -P "$(dirname -- "$file")"
+    file="$PWD/$(basename -- "$file")"
+  done
+  echo "$file"
+)
+
+SCRIPT_DIR=$(follow_links "$(dirname -- "${BASH_SOURCE[0]}")")
+FLUTTER_DIR="$(cd "$SCRIPT_DIR/.."; pwd -P)"
+
+cd "$FLUTTER_DIR"
 
 if git remote get-url upstream >/dev/null 2>&1; then
   UPSTREAM=upstream/master
@@ -7,7 +39,7 @@ else
 fi;
 
 FLUTTER_VERSION="$(curl -s https://raw.githubusercontent.com/flutter/flutter/master/bin/internal/engine.version)"
-BEHIND="$(git rev-list $FLUTTER_VERSION..$UPSTREAM --oneline | wc -l)"
+BEHIND="$(git rev-list "$FLUTTER_VERSION".."$UPSTREAM" --oneline | wc -l)"
 MAX_BEHIND=16 # no more than 4 bisections to identify the issue
 
 if [[ $BEHIND -le $MAX_BEHIND ]]; then
@@ -18,4 +50,3 @@ else
   echo "       please roll engine into flutter first before merging more commits into engine."
   exit 1
 fi
-
diff --git a/engine/src/flutter/ci/firebase_testlab.sh b/engine/src/flutter/ci/firebase_testlab.sh
index 76540ebcb2a..45631d9bfd0 100755
--- a/engine/src/flutter/ci/firebase_testlab.sh
+++ b/engine/src/flutter/ci/firebase_testlab.sh
@@ -1,16 +1,26 @@
 #!/bin/bash
+#
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
 
 set -e
 
-if [[ ! -f $1 ]]; then
-  echo "File $1 not found."
-  exit -1
+APP="$1"
+if [[ -z "$APP" ]]; then
+  echo "Application must be specified as the first argument to the script."
+  exit 255
 fi
 
-GIT_REVISION=${2:-$(git rev-parse HEAD)}
-BUILD_ID=${3:-$CIRRUS_BUILD_ID}
+if [[ ! -f "$APP" ]]; then
+  echo "File '$APP' not found."
+  exit 255
+fi
 
-if [[ ! -z $GCLOUD_FIREBASE_TESTLAB_KEY ]]; then
+GIT_REVISION="${2:-$(git rev-parse HEAD)}"
+BUILD_ID="${3:-$CIRRUS_BUILD_ID}"
+
+if [[ -n $GCLOUD_FIREBASE_TESTLAB_KEY ]]; then
   # New contributors will not have permissions to run this test - they won't be
   # able to access the service account information. We should just mark the test
   # as passed - it will run fine on post submit, where it will still catch
@@ -21,8 +31,8 @@ if [[ ! -z $GCLOUD_FIREBASE_TESTLAB_KEY ]]; then
     exit 0
   fi
 
-  echo $GCLOUD_FIREBASE_TESTLAB_KEY > ${HOME}/gcloud-service-key.json
-  gcloud auth activate-service-account --key-file=${HOME}/gcloud-service-key.json
+  echo "$GCLOUD_FIREBASE_TESTLAB_KEY" > "${HOME}/gcloud-service-key.json"
+  gcloud auth activate-service-account --key-file="${HOME}/gcloud-service-key.json"
 fi
 
 # Run the test.
@@ -32,8 +42,8 @@ fi
 # See https://firebase.google.com/docs/test-lab/android/game-loop
 gcloud --project flutter-infra firebase test android run \
   --type game-loop \
-  --app $1 \
+  --app "$APP" \
   --timeout 2m \
   --results-bucket=gs://flutter_firebase_testlab \
-  --results-dir=engine_scenario_test/$GIT_REVISION/$BUILD_ID \
+  --results-dir="engine_scenario_test/$GIT_REVISION/$BUILD_ID" \
   --no-auto-google-login
diff --git a/engine/src/flutter/ci/format.sh b/engine/src/flutter/ci/format.sh
index ff45d2ad8b4..18e3279212f 100755
--- a/engine/src/flutter/ci/format.sh
+++ b/engine/src/flutter/ci/format.sh
@@ -1,18 +1,77 @@
 #!/bin/bash
 #
-# Code formatting presubmit
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Code formatting presubmit script.
 #
 # This presubmit script ensures that code under the src/flutter directory is
-# formatted according to the Flutter engine style requirements. On failure, a
-# diff is emitted that can be applied from within the src/flutter directory
-# via:
+# formatted according to the Flutter engine style requirements.
 #
-# patch -p0 < diff.patch
+# If failures are found, they can be fixed by re-running the script with the
+# --fix option.
 
 set -e
-echo "Checking formatting..."
 
-case "$(uname -s)" in
+# Needed because if it is set, cd may print the path it changed to.
+unset CDPATH
+
+# On Mac OS, readlink -f doesn't work, so follow_links traverses the path one
+# link at a time, and then cds into the link destination and find out where it
+# ends up.
+#
+# The function is enclosed in a subshell to avoid changing the working directory
+# of the caller.
+function follow_links() (
+  cd -P "$(dirname -- "$1")"
+  file="$PWD/$(basename -- "$1")"
+  while [[ -h "$file" ]]; do
+    cd -P "$(dirname -- "$file")"
+    file="$(readlink -- "$file")"
+    cd -P "$(dirname -- "$file")"
+    file="$PWD/$(basename -- "$file")"
+  done
+  echo "$file"
+)
+
+SCRIPT_DIR=$(follow_links "$(dirname -- "${BASH_SOURCE[0]}")")
+SRC_DIR="$(
+  cd "$SCRIPT_DIR/../.."
+  pwd -P
+)"
+FLUTTER_DIR="$SRC_DIR/flutter"
+
+function message() {
+  echo "$*" 1>&2
+}
+
+function error() {
+  echo "ERROR: $*" 1>&2
+}
+
+function warning() {
+  echo "WARNING: $*" 1>&2
+}
+
+function get_base_sha() (
+  local upstream
+  if git remote get-url upstream >/dev/null 2>&1; then
+    upstream=upstream
+  else
+    upstream=origin
+  fi
+
+  cd "$FLUTTER_DIR"
+  git fetch "$upstream" master >/dev/null 2>&1
+  git merge-base --fork-point FETCH_HEAD HEAD || git merge-base FETCH_HEAD HEAD
+)
+
+function check_clang_format() (
+  cd "$FLUTTER_DIR"
+  message "Checking C++/ObjC formatting..."
+
+  case "$(uname -s)" in
   Darwin)
     OS="mac-x64"
     ;;
@@ -20,81 +79,177 @@ case "$(uname -s)" in
     OS="linux-x64"
     ;;
   *)
-    echo "Unknown operating system."
-    exit -1
+    error "Unknown operating system."
+    return 255
     ;;
-esac
+  esac
 
-# Tools
-CLANG_FORMAT="../buildtools/$OS/clang/bin/clang-format"
-$CLANG_FORMAT --version
+  # Tools
+  local clang_format="$SRC_DIR/buildtools/$OS/clang/bin/clang-format"
+  "$clang_format" --version 1>&2
 
-# Compute the diffs.
-CLANG_FILETYPES="*.c *.cc *.cpp *.h *.m *.mm"
-DIFF_OPTS="-U0 --no-color --name-only"
+  local current_diff
+  local clang_files_to_check
 
-if git remote get-url upstream >/dev/null 2>&1; then
-  UPSTREAM=upstream
-else
-  UPSTREAM=origin
-fi;
-
-
-BASE_SHA="$(git fetch $UPSTREAM master > /dev/null 2>&1 && \
-           (git merge-base --fork-point FETCH_HEAD HEAD || git merge-base FETCH_HEAD HEAD))"
-# Disable glob matching otherwise a file in the current directory that matches
-# $CLANG_FILETYPES will cause git to query for that exact file instead of doing
-# a match.
-set -f
-CLANG_FILES_TO_CHECK="$(git ls-files $CLANG_FILETYPES)"
-set +f
-FAILED_CHECKS=0
-for f in $CLANG_FILES_TO_CHECK; do
-  set +e
-  CUR_DIFF="$(diff -u "$f" <("$CLANG_FORMAT" --style=file "$f"))"
-  set -e
-  if [[ ! -z "$CUR_DIFF" ]]; then
-    echo "$CUR_DIFF"
-    FAILED_CHECKS=$(($FAILED_CHECKS+1))
-  fi
-done
-
-GOOGLE_JAVA_FORMAT="../third_party/android_tools/google-java-format/google-java-format-1.7-all-deps.jar"
-if [[ -f "$GOOGLE_JAVA_FORMAT" && -f "$(which java)" ]]; then
-  java -jar "$GOOGLE_JAVA_FORMAT" --version 2>&1
-  JAVA_FILETYPES="*.java"
-  JAVA_FILES_TO_CHECK="$(git diff $DIFF_OPTS $BASE_SHA -- $JAVA_FILETYPES)"
-  for f in $JAVA_FILES_TO_CHECK; do
+  # Compute the diffs.
+  local clang_filetypes=("*.c" "*.cc" "*.cpp" "*.h" "*.m" "*.mm")
+  clang_files_to_check="$(git ls-files "${clang_filetypes[@]}")"
+  local failed_clang_checks=0
+  for file in $clang_files_to_check; do
     set +e
-    CUR_DIFF="$(diff -u "$f" <(java -jar "$GOOGLE_JAVA_FORMAT" "$f"))"
+    current_diff="$(diff -u "$file" <("$clang_format" --style=file "$file"))"
     set -e
-    if [[ ! -z "$CUR_DIFF" ]]; then
-      echo "$CUR_DIFF"
-      FAILED_CHECKS=$(($FAILED_CHECKS+1))
+    if [[ -n "$current_diff" ]]; then
+      echo "$current_diff"
+      failed_clang_checks=$((failed_clang_checks + 1))
     fi
   done
+
+  if [[ $failed_clang_checks -ne 0 ]]; then
+    error "$failed_clang_checks C++/ObjC files are formatted incorrectly."
+  fi
+  return $failed_clang_checks
+)
+
+function check_java_format() (
+  cd "$FLUTTER_DIR"
+  local diff_opts=("-U0" "--no-color" "--name-only")
+  message "Checking Java formatting..."
+  local google_java_format="$SRC_DIR/third_party/android_tools/google-java-format/google-java-format-1.7-all-deps.jar"
+  local failed_java_checks=0
+  if [[ -f "$google_java_format" && -n "$(command -v java)" ]]; then
+    java -jar "$google_java_format" --version 1>&2
+    local java_filetypes=("*.java")
+    local java_files_to_check
+    java_files_to_check="$(git diff "${diff_opts[@]}" "$BASE_SHA" -- "${java_filetypes[@]}")"
+    for file in $java_files_to_check; do
+      set +e
+      current_diff="$(diff -u "$file" <(java -jar "$google_java_format" "$file"))"
+      set -e
+      if [[ -n "$current_diff" ]]; then
+        echo "$current_diff"
+        failed_java_checks=$((failed_java_checks + 1))
+      fi
+    done
+    if [[ $failed_java_checks -ne 0 ]]; then
+      error "$failed_java_checks Java files are formatted incorrectly."
+    fi
+  else
+    warning "Cannot find google-java-format, skipping Java file formatting!"
+  fi
+  return $failed_java_checks
+)
+
+# Strips off the "advice" at the end, since this script has different advice.
+function do_gn_check() {
+  local output
+  output="$("$SCRIPT_DIR/check_gn_format.py" --dry-run --root-directory . --gn-binary "third_party/gn/gn")"
+  local result=$?
+  echo "$output" | grep "ERROR"
+  return $result
+}
+
+function check_gn_format() (
+  cd "$FLUTTER_DIR"
+  message "Checking GN formatting..."
+  if ! do_gn_check 1>&2; then
+    error "The gn file format check failed."
+    return 1
+  fi
+)
+
+function check_whitespace() (
+  local diff_opts=("-U0" "--no-color" "--name-only")
+  local filetypes="*.dart"
+  local trailing_spaces
+
+  message "Checking for trailing whitespace in $filetypes files..." 1>&2
+  set +e
+  trailing_spaces=$(git diff "${diff_opts[@]}" "$BASE_SHA" -- "$filetypes" | xargs grep --line-number --with-filename '[[:blank:]]\+$')
+  set -e
+
+  if [[ -n "$trailing_spaces" ]]; then
+    message "$trailing_spaces"
+    error "Whitespace check failed. The above files have trailing spaces."
+    return 1
+  fi
+)
+
+function fix_clang_format() {
+  local tmpfile
+  tmpfile=$(mktemp "fix_clang_format.XXXXXX")
+  if check_clang_format >"$tmpfile"; then
+    message "No C++/ObjC formatting issues found."
+  else
+    message "Fixing C++/ObjC formatting issues."
+    (
+      cd "$SRC_DIR/flutter"
+      patch -p0 <"$tmpfile"
+    )
+  fi
+  command rm -f "$tmpfile"
+}
+
+function fix_java_format() {
+  local tmpfile
+  tmpfile=$(mktemp "fix_java_format.XXXXXX")
+  if check_java_format >"$tmpfile"; then
+    message "No Java formatting issues found."
+  else
+    message "Fixing Java formatting issues."
+    (
+      cd "$SRC_DIR/flutter"
+      patch -p0 <"$tmpfile"
+    )
+  fi
+  command rm -f "$tmpfile"
+}
+
+function fix_gn_format() (
+  cd "$FLUTTER_DIR"
+  message "Fixing GN formatting..."
+  # Check GN format consistency and fix it.
+  if ! "$SCRIPT_DIR/check_gn_format.py" --root-directory . --gn-binary "third_party/gn/gn"; then
+    error "The GN file format fix failed."
+    return 1
+  fi
+)
+
+function fix_whitespace() {
+  if ! check_whitespace; then
+    message "Fixing trailing whitespace problems."
+    find "$FLUTTER_DIR" -type f -name "*.dart" -print0 | xargs -0 sed -i -e 's/\s\+$//'
+  fi
+}
+
+BASE_SHA=$(get_base_sha)
+message "Checking formatting for files with differences from $BASE_SHA in $FLUTTER_DIR"
+
+if [[ $1 == "--fix" ]]; then
+  fix_clang_format
+  fix_java_format
+  fix_gn_format
+  fix_whitespace
+  message "Formatting fixed."
 else
-  echo "WARNING: Cannot find google-java-format, skipping Java file formatting!"
+  failures=0
+  if ! check_clang_format; then
+    failures=$((failures + 1))
+  fi
+  if ! check_java_format; then
+    failures=$((failures + 1))
+  fi
+  if ! check_gn_format; then
+    failures=$((failures + 1))
+  fi
+  if ! check_whitespace; then
+    failures=$((failures + 1))
+  fi
+  if [[ $failures -eq 0 ]]; then
+    message "No formatting issues found."
+  else
+    error "Formatting check failed."
+    error "To fix, run \"$SCRIPT_DIR/format.sh --fix\""
+  fi
+  exit $failures
 fi
-
-if [[ $FAILED_CHECKS -ne 0 ]]; then
-  echo ""
-  echo "ERROR: Some files are formatted incorrectly. To fix, run \`./ci/format.sh | patch -p0\` from the flutter/engine/src/flutter directory."
-  exit 1
-fi
-
-FILETYPES="*.dart"
-
-set +e
-TRAILING_SPACES=$(git diff $DIFF_OPTS $BASE_SHA..HEAD -- $FILETYPES | xargs grep --line-number --with-filename '[[:blank:]]\+$')
-set -e
-
-if [[ ! -z "$TRAILING_SPACES" ]]; then
-  echo "$TRAILING_SPACES"
-  echo ""
-  echo "ERROR: Some files have trailing spaces. To fix, try something like \`find . -name "*.dart" -exec sed -i -e 's/\s\+$//' {} \;\`."
-  exit 1
-fi
-
-# Check GN format consistency
-./ci/check_gn_format.py --dry-run --root-directory . --gn-binary "third_party/gn/gn"
diff --git a/engine/src/flutter/ci/licenses.sh b/engine/src/flutter/ci/licenses.sh
index 58b06ea8a17..48843bf58d7 100755
--- a/engine/src/flutter/ci/licenses.sh
+++ b/engine/src/flutter/ci/licenses.sh
@@ -1,81 +1,140 @@
 #!/bin/bash
+#
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
 set -e
 shopt -s nullglob
 
-echo "Verifying license script is still happy..."
-echo "Using pub from `which pub`, dart from `which dart`"
+# Needed because if it is set, cd may print the path it changed to.
+unset CDPATH
 
-exitStatus=0
+# On Mac OS, readlink -f doesn't work, so follow_links traverses the path one
+# link at a time, and then cds into the link destination and find out where it
+# ends up.
+#
+# The function is enclosed in a subshell to avoid changing the working directory
+# of the caller.
+function follow_links() (
+  cd -P "$(dirname -- "$1")"
+  file="$PWD/$(basename -- "$1")"
+  while [[ -h "$file" ]]; do
+    cd -P "$(dirname -- "$file")"
+    file="$(readlink -- "$file")"
+    cd -P "$(dirname -- "$file")"
+    file="$PWD/$(basename -- "$file")"
+  done
+  echo "$file"
+)
+
+SCRIPT_DIR=$(follow_links "$(dirname -- "${BASH_SOURCE[0]}")")
+SRC_DIR="$(cd "$SCRIPT_DIR/../.."; pwd -P)"
+DART_BIN="$SRC_DIR/third_party/dart/tools/sdks/dart-sdk/bin"
+PATH="$DART_BIN:$PATH"
+
+echo "Verifying license script is still happy..."
+echo "Using pub from $(command -v pub), dart from $(command -v dart)"
+
+untracked_files="$(cd "$SRC_DIR/flutter"; git status --ignored --short | grep -E "^!" | awk "{print\$2}")"
+untracked_count="$(echo "$untracked_files" | wc -l)"
+if [[ $untracked_count -gt 0 ]]; then
+  echo ""
+  echo "WARNING: There are $untracked_count untracked/ignored files or directories in the flutter repository."
+  echo "False positives may occur."
+  echo "You can use 'git clean -dxf' in the flutter dir to clean out these files."
+  echo "BUT, be warned that this will recursively remove all these files and directories:"
+  echo "$untracked_files"
+  echo ""
+fi
 
 dart --version
 
-# These files trip up the script on Mac OS X.
-find . -name ".DS_Store" -exec rm {} \;
+# Collects the license information from the repo.
+# Runs in a subshell.
+function collect_licenses() (
+  cd "$SRC_DIR/flutter/tools/licenses"
+  pub get
+  dart --enable-asserts lib/main.dart         \
+    --src ../../..                            \
+    --out ../../../out/license_script_output  \
+    --golden ../../ci/licenses_golden
+)
 
-(cd flutter/tools/licenses; pub get; dart --enable-asserts lib/main.dart --src ../../.. --out ../../../out/license_script_output --golden ../../ci/licenses_golden)
+# Verifies the licenses in the repo.
+# Runs in a subshell.
+function verify_licenses() (
+  local exitStatus=0
+  cd "$SRC_DIR"
 
-for f in out/license_script_output/licenses_*; do
-    if ! cmp -s flutter/ci/licenses_golden/$(basename $f) $f
-    then
-        echo "============================= ERROR ============================="
-        echo "License script got different results than expected for $f."
-        echo "Please rerun the licenses script locally to verify that it is"
-        echo "correctly catching any new licenses for anything you may have"
-        echo "changed, and then update this file:"
-        echo "  flutter/sky/packages/sky_engine/LICENSE"
-        echo "For more information, see the script in:"
-        echo "  https://github.com/flutter/engine/tree/master/tools/licenses"
-        echo ""
-        diff -U 6 flutter/ci/licenses_golden/$(basename $f) $f
-        echo "================================================================="
-        echo ""
-        exitStatus=1
-    fi
-done
+  # These files trip up the script on Mac OS X.
+  find . -name ".DS_Store" -exec rm {} \;
 
-echo "Verifying license tool signature..."
-if ! cmp -s flutter/ci/licenses_golden/tool_signature out/license_script_output/tool_signature
-then
-    echo "============================= ERROR ============================="
-    echo "The license tool signature has changed. This is expected when"
-    echo "there have been changes to the license tool itself. Licenses have"
-    echo "been re-computed for all components. If only the license script has"
-    echo "changed, no diffs are typically expected in the output of the"
-    echo "script. Verify the output, and if it looks correct, update the"
-    echo "license tool signature golden file:"
-    echo "  ci/licenses_golden/tool_signature"
-    echo "For more information, see the script in:"
-    echo "  https://github.com/flutter/engine/tree/master/tools/licenses"
-    echo ""
-    diff -U 6 flutter/ci/licenses_golden/tool_signature out/license_script_output/tool_signature
-    echo "================================================================="
-    echo ""
-    exitStatus=1
-fi
+  collect_licenses
 
-echo "Checking license count in licenses_flutter..."
-actualLicenseCount=`tail -n 1 flutter/ci/licenses_golden/licenses_flutter | tr -dc '0-9'`
-expectedLicenseCount=2 # When changing this number: Update the error message below as well describing all expected license types.
+  for f in out/license_script_output/licenses_*; do
+      if ! cmp -s "flutter/ci/licenses_golden/$(basename "$f")" "$f"; then
+          echo "============================= ERROR ============================="
+          echo "License script got different results than expected for $f."
+          echo "Please rerun the licenses script locally to verify that it is"
+          echo "correctly catching any new licenses for anything you may have"
+          echo "changed, and then update this file:"
+          echo "  flutter/sky/packages/sky_engine/LICENSE"
+          echo "For more information, see the script in:"
+          echo "  https://github.com/flutter/engine/tree/master/tools/licenses"
+          echo ""
+          diff -U 6 "flutter/ci/licenses_golden/$(basename "$f")" "$f"
+          echo "================================================================="
+          echo ""
+          exitStatus=1
+      fi
+  done
 
-if [ "$actualLicenseCount" -ne "$expectedLicenseCount" ]
-then
-    echo "=============================== ERROR ==============================="
-    echo "The total license count in flutter/ci/licenses_golden/licenses_flutter"
-    echo "changed from $expectedLicenseCount to $actualLicenseCount."
-    echo "It's very likely that this is an unintentional change. Please"
-    echo "double-check that all newly added files have a BSD-style license"
-    echo "header with the following copyright:"
-    echo "    Copyright 2013 The Flutter Authors. All rights reserved."
-    echo "Files in 'third_party/txt' may have an Apache license header instead."
-    echo "If you're absolutely sure that the change in license count is"
-    echo "intentional, update 'flutter/ci/licenses.sh' with the new count."
-    echo "================================================================="
-    echo ""
-    exitStatus=1
-fi
+  echo "Verifying license tool signature..."
+  if ! cmp -s "flutter/ci/licenses_golden/tool_signature" "out/license_script_output/tool_signature"; then
+      echo "============================= ERROR ============================="
+      echo "The license tool signature has changed. This is expected when"
+      echo "there have been changes to the license tool itself. Licenses have"
+      echo "been re-computed for all components. If only the license script has"
+      echo "changed, no diffs are typically expected in the output of the"
+      echo "script. Verify the output, and if it looks correct, update the"
+      echo "license tool signature golden file:"
+      echo "  ci/licenses_golden/tool_signature"
+      echo "For more information, see the script in:"
+      echo "  https://github.com/flutter/engine/tree/master/tools/licenses"
+      echo ""
+      diff -U 6 "flutter/ci/licenses_golden/tool_signature" "out/license_script_output/tool_signature"
+      echo "================================================================="
+      echo ""
+      exitStatus=1
+  fi
 
-if [ "$exitStatus" -eq "0" ]
-then
-  echo "Licenses are as expected."
-fi
-exit $exitStatus
+  echo "Checking license count in licenses_flutter..."
+
+  local actualLicenseCount
+  actualLicenseCount="$(tail -n 1 flutter/ci/licenses_golden/licenses_flutter | tr -dc '0-9')"
+  local expectedLicenseCount=2 # When changing this number: Update the error message below as well describing all expected license types.
+
+  if [[ $actualLicenseCount -ne $expectedLicenseCount ]]; then
+      echo "=============================== ERROR ==============================="
+      echo "The total license count in flutter/ci/licenses_golden/licenses_flutter"
+      echo "changed from $expectedLicenseCount to $actualLicenseCount."
+      echo "It's very likely that this is an unintentional change. Please"
+      echo "double-check that all newly added files have a BSD-style license"
+      echo "header with the following copyright:"
+      echo "    Copyright 2013 The Flutter Authors. All rights reserved."
+      echo "Files in 'third_party/txt' may have an Apache license header instead."
+      echo "If you're absolutely sure that the change in license count is"
+      echo "intentional, update 'flutter/ci/licenses.sh' with the new count."
+      echo "================================================================="
+      echo ""
+      exitStatus=1
+  fi
+
+  if [[ $exitStatus -eq 0 ]]; then
+    echo "Licenses are as expected."
+  fi
+  return $exitStatus
+)
+
+verify_licenses
\ No newline at end of file
diff --git a/engine/src/flutter/ci/lint.sh b/engine/src/flutter/ci/lint.sh
index d6da6805506..e2698f255f7 100755
--- a/engine/src/flutter/ci/lint.sh
+++ b/engine/src/flutter/ci/lint.sh
@@ -1,9 +1,10 @@
 #!/bin/bash
+#
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
 
 set -e
-SCRIPT_DIR=`realpath $(dirname "${BASH_SOURCE[0]}")`
-DART="${SCRIPT_DIR}/../../third_party/dart/tools/sdks/dart-sdk/bin/dart"
-PUB="${SCRIPT_DIR}/../../third_party/dart/tools/sdks/dart-sdk/bin/pub"
 
 # Needed because if it is set, cd may print the path it changed to.
 unset CDPATH
@@ -12,15 +13,6 @@ unset CDPATH
 # link at a time, and then cds into the link destination and find out where it
 # ends up.
 #
-# The returned filesystem path must be a format usable by Dart's URI parser,
-# since the Dart command line tool treats its argument as a file URI, not a
-# filename. For instance, multiple consecutive slashes should be reduced to a
-# single slash, since double-slashes indicate a URI "authority", and these are
-# supposed to be filenames. There is an edge case where this will return
-# multiple slashes: when the input resolves to the root directory. However, if
-# that were the case, we wouldn't be running this shell, so we don't do anything
-# about it.
-#
 # The function is enclosed in a subshell to avoid changing the working directory
 # of the caller.
 function follow_links() (
@@ -34,17 +26,20 @@ function follow_links() (
   done
   echo "$file"
 )
-PROG_NAME="$(follow_links "${BASH_SOURCE[0]}")"
-CI_DIR="$(cd "${PROG_NAME%/*}" ; pwd -P)"
-SRC_DIR="$(cd "$CI_DIR/../.."; pwd -P)"
+
+SCRIPT_DIR=$(follow_links "$(dirname -- "${BASH_SOURCE[0]}")")
+SRC_DIR="$(cd "$SCRIPT_DIR/../.."; pwd -P)"
+DART_BIN="${SRC_DIR}/third_party/dart/tools/sdks/dart-sdk/bin"
+DART="${DART_BIN}/dart"
+PUB="${DART_BIN}/pub"
 
 COMPILE_COMMANDS="$SRC_DIR/out/compile_commands.json"
 if [ ! -f "$COMPILE_COMMANDS" ]; then
-  (cd $SRC_DIR; ./flutter/tools/gn)
+  (cd "$SRC_DIR"; ./flutter/tools/gn)
 fi
 
-cd "$CI_DIR"
-$PUB get && $DART \
+cd "$SCRIPT_DIR"
+"$PUB" get && "$DART" \
   --disable-dart-dev \
   bin/lint.dart \
   --compile-commands="$COMPILE_COMMANDS" \
diff --git a/engine/src/flutter/ci/pubspec.yaml b/engine/src/flutter/ci/pubspec.yaml
index d345cab6e78..d1fdcd85970 100644
--- a/engine/src/flutter/ci/pubspec.yaml
+++ b/engine/src/flutter/ci/pubspec.yaml
@@ -1,9 +1,13 @@
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
 name: ci_scripts
 
 dependencies:
   args: ^1.6.0
   path: ^1.7.0
-  process_runner: ^2.0.3
+  process_runner: ^3.0.0
 
 environment:
   sdk: '>=2.8.0 <3.0.0'
diff --git a/engine/src/flutter/ci/test.sh b/engine/src/flutter/ci/test.sh
deleted file mode 100755
index c0ea5babca9..00000000000
--- a/engine/src/flutter/ci/test.sh
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/bin/bash
-
-cd frontend_server
-dart test/server_test.dart