diff --git a/sky/BUILD.gn b/sky/BUILD.gn
index 7286d878e7f..dec693b28bf 100644
--- a/sky/BUILD.gn
+++ b/sky/BUILD.gn
@@ -7,6 +7,7 @@ import("//sky/engine/bindings/bindings.gni")
 declare_args() {
   enable_gcm = false
   enable_firebase = false
+  enable_google_sign_in = false
 }
 
 group("sky") {
@@ -48,4 +49,8 @@ group("sky") {
   if (enable_gcm) {
     deps += [ "//third_party/gcm:gcm" ]
   }
+
+  if (enable_google_sign_in) {
+    deps += [ "//third_party/google_sign_in" ]
+  }
 }
diff --git a/sky/services/dynamic/README.md b/sky/services/dynamic/README.md
index c44f29ef16f..a0d96a5beb0 100644
--- a/sky/services/dynamic/README.md
+++ b/sky/services/dynamic/README.md
@@ -1,4 +1,4 @@
 Flutter Dynamic Services Loader
 ===============================
 
-Third party service implementations are packaged as dylibs. Each dylib implementation needs to import just one file (`dynamic_service_dylib.h`) and implement `FlutterServicePerform` to provide the service implementation. In order to build the dylib, the build step needs the `//sky/services/dynamic:dylib` GN rule.
\ No newline at end of file
+Third party service implementations are packaged as dylibs. Each dylib implementation needs to import just one file (`dynamic_service_dylib.h`) and implement `FlutterServicePerform` to provide the service implementation. In order to build the dylib, the build step needs the `//sky/services/dynamic:sdk_lib` GN rule.
diff --git a/sky/shell/platform/ios/FlutterAppDelegate.mm b/sky/shell/platform/ios/FlutterAppDelegate.mm
index e88f7cbcb52..d8e57eb3e92 100644
--- a/sky/shell/platform/ios/FlutterAppDelegate.mm
+++ b/sky/shell/platform/ios/FlutterAppDelegate.mm
@@ -58,4 +58,25 @@ NSURL* URLForSwitch(const char* name) {
   return YES;
 }
 
+// Use the NSNotificationCenter to notify services when we're opened with URLs.
+// TODO(jackson): Revisit this API once we have more services using URLs to make
+// it more typed and less brittle
+- (BOOL)application:(UIApplication *)app
+            openURL:(NSURL *)url
+            sourceApplication:(NSString *)sourceApplication
+            annotation:(id)annotation
+{
+  NSDictionary *dict = [@{
+    @"handled": [NSMutableDictionary dictionary],
+    @"url": url,
+    @"sourceApplication": sourceApplication,
+  } mutableCopy];
+  if (annotation != nil)
+    [dict setValue:annotation forKey:@"annotation"];
+  [[NSNotificationCenter defaultCenter] postNotificationName:@"openURL"
+                                                      object:self
+                                                    userInfo:dict];
+  BOOL handled = ((NSNumber *)dict[@"handled"][@"value"]).boolValue;
+  return handled;
+}
 @end
diff --git a/sky/tools/gn b/sky/tools/gn
index 57cf713b253..20453678f97 100755
--- a/sky/tools/gn
+++ b/sky/tools/gn
@@ -97,6 +97,7 @@ def to_gn_args(args):
 
     gn_args['enable_firebase'] = args.enable_firebase
     gn_args['enable_gcm'] = args.enable_gcm
+    gn_args['enable_google_sign_in'] = args.enable_google_sign_in
     gn_args['use_glfw'] = args.use_glfw
 
     return gn_args
@@ -126,6 +127,7 @@ def parse_args(args):
 
   parser.add_argument('--enable-firebase', action='store_true', default=False)
   parser.add_argument('--enable-gcm', action='store_true', default=False)
+  parser.add_argument('--enable-google-sign-in', action='store_true', default=False)
   parser.add_argument('--use-glfw', action='store_true', default=False)
 
   return parser.parse_args(args)