Make a reftest for the flights app.

This way we get some broad pixel test coverage.
Do this by dumping the png from the flights app,
uploading it to google storage and then having
the reference file load the uploaded file.

This isn't a good long-term solution. Long-term
we should dump paint commands (or some other
textual representation) and/or make more targetted
reftests that don't need pngs. As such, the process
for doing this is painful and manual. If we decide
we want to have pixel tests properly, we'll want
to do something more automated obviously.

Also, turn on the discard_transparency bool when
encoding the pngs. Otherwise, the png is lossy
and none of this works.

R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/836363003

HACKING.md

@@ -41,3 +41,27 @@ describe('My pretty test of my subject', function() {
   });
 });
 ```
+
+Adding pixel tests
+------------------
+
+Sky does not have proper pixel tests. Instead we have only reftests.
+If you want a pixel test, you need to dump the png from a reftest,
+upload it to googlestorage and then put and <img> pointing to the
+uploaded file in the reference.
+
+1. Create your test (e.g. foo.sky).
+2. Create an dummy reference file (foo-expected.sky).
+3. Run the test (it will fail).
+4. Copy the -actual.png file to googlestorage (see below).
+5. Put an <img> pointing to your newly uploaded png in the reference file.
+
+Copying the file to googlestorage:
+$ sha1sum ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png
+db0508cdfe69e996a93464050dc383f6480f1283  ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png
+$ gsutil.py cp ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png gs://mojo/sky-pngs/db0508cdfe69e996a93464050dc383f6480f1283
+
+Long-term, we should not have these tests at all and should just
+dump paint commands. In the short-term, if we find we're doing this
+a lot we should obviously automate this process, e.g. test_sky could
+do all of this work, including spitting out the correct reference file.

compositor/display_delegate_bitmap.cc

@@ -22,7 +22,7 @@ DisplayDelegate* DisplayDelegateBitmap::create(LayerClient* client) {
 }
 
 void DisplayDelegateBitmap::GetPixelsForTesting(std::vector<unsigned char>* pixels) {
-  gfx::PNGCodec::EncodeBGRASkBitmap(bitmap_, false, pixels);
+  gfx::PNGCodec::EncodeBGRASkBitmap(bitmap_, true, pixels);
 }
 
 void DisplayDelegateBitmap::Paint(mojo::GaneshSurface& surface, const gfx::Rect& size) {

tests/framework/flights-app-pixels-expected.sky

@@ -0,0 +1,13 @@
+<sky>
+  <import src="../resources/run-after-display.sky" as="runAfterDisplay" />
+
+  <img src="http://storage.googleapis.com/mojo/sky-pngs/db0508cdfe69e996a93464050dc383f6480f1283" />
+
+  <script>
+    window.addEventListener('load', function() {
+      runAfterDisplay(function() {
+        internals.notifyTestComplete("");
+      });
+    });
+  </script>
+</sky>

tests/framework/flights-app-pixels.sky

@@ -0,0 +1,13 @@
+<sky>
+  <import src="../resources/run-after-display.sky" as="runAfterDisplay" />
+  <import src="/sky/examples/flights-app/flights-app.sky" />
+  <script>
+  addEventListener("load", function() {
+    var app = document.createElement("flights-app");
+    document.querySelector("sky").appendChild(app);
+    runAfterDisplay(function() {
+      internals.notifyTestComplete("");
+    });
+  });
+  </script>
+</sky>