Add a manifest parameter to flutter_app. (#3268)

This will ensure the flx file is rebuilt whenever the manifest is modified.

build/flutter_app.gni

@@ -22,6 +22,9 @@ import("//build/dart/dart_package.gni")
 #   deps (optional)
 #     List of Dart packages the application depends on.
 #
+#   manifest (optional)
+#     Path to the manifest file
+#
 #   analysis_options (optional)
 #     By default, a script to run the analyzer on the contents of the package is
 #     generated in the output directory. This parameter contains the path to an
@@ -122,6 +125,9 @@ template("flutter_app") {
     inputs = [
       snapshot_path,
     ]
+    if (defined(invoker.manifest)) {
+      inputs += [ rebase_path(invoker.manifest) ]
+    }
 
     outputs = [
       bundle_path,
@@ -151,6 +157,12 @@ template("flutter_app") {
       "--snapshot",
       rebase_path(snapshot_path),
     ]
+    if (defined(invoker.manifest)) {
+      args += [
+        "--manifest",
+        rebase_path(invoker.manifest)
+      ]
+    }
 
     deps = [
       ":$flutter_snapshot_name",

build/package.py

@@ -32,6 +32,7 @@ def main():
                       help='Path to application snapshot')
   parser.add_argument('--output-file', type=str, required=True,
                       help='Where to output application bundle')
+  parser.add_argument('--manifest', type=str, help='The application manifest')
 
   args = parser.parse_args()
 
@@ -39,7 +40,7 @@ def main():
   env['LD_LIBRARY_PATH'] = args.root
   env['FLUTTER_ROOT'] = args.flutter_root
 
-  result = subprocess.call([
+  call_args = [
     args.dart,
     '--packages=%s' % args.flutter_tools_packages,
     args.flutter_tools_main,
@@ -48,7 +49,11 @@ def main():
     '--snapshot=%s' % args.snapshot,
     '--output-file=%s' % args.output_file,
     '--header=#!fuchsia file:///system/apps/flutter_runner',
-  ], env=env, cwd=args.app_dir)
+  ]
+  if 'manifest' in args:
+    call_args.append('--manifest=%s' % args.manifest)
+
+  result = subprocess.call(call_args, env=env, cwd=args.app_dir)
 
   return result