Load application manifests from resources

mojo/public/mojo_application_manifest.gni

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Used to produce a Mojo Application Manifest for an application.
 #
 # Parameters:
 #
 #   source
 #       The manifest file template for this application, must be valid JSON with
 #       a valid 'url' key matching application_name.
 #
+#   base_manifest (optional)
+#       A manifest file template to use as a base for |source|. Any properties
+#       defined in |source| will overwrite or be merged with properties defined
+#       in |base_manifest|.
+#
 #   application_name
 #       The host portion of the mojo: URL of the application. The script
 #       validates that the value of this parameter matches the host name portion
 #       of the 'url' property set in the manifest and throws a ValueError if
 #       they do not.
 #
+#   base_deps (optional)
+#       Dependencies required to generate |base_manifest| if applicable.
+#
 #   deps (optional)
 #       An array of dependent instances of this template. This template enforces
 #       that dependencies can only be instances of this template.
 #
 #   packaged_applications (optional)
 #       An array of application_names of the dependent applications.
 #
 #   type (default is mojo)
 #       Possible values are 'mojo' and 'exe'. Default is 'mojo'.
 #
@@ skipping 48 matching lines @@
 
     rebase_parent = rebase_path(invoker.source, root_build_dir)
     rebase_output = rebase_path(output, root_build_dir)
 
     args = [
       "--application-name=$application_name",
       "--parent=$rebase_parent",
       "--output=$rebase_output",
     ]
 
+    if (defined(invoker.base_manifest)) {
+      rebase_base = rebase_path(invoker.base_manifest, root_build_dir)
+      args += [ "--base-manifest=$rebase_base" ]
+    }
+
     if (defined(invoker.packaged_applications)) {
       foreach(application_name, invoker.packaged_applications) {
         input = "$root_out_dir/$application_name/manifest.json"
         inputs += [ input ]
         args += [ rebase_path(input, root_build_dir) ]
       }
     }
     deps = []
     if (defined(invoker.deps)) {
       deps += invoker.deps
     }
+    if (defined(invoker.base_deps)) {
+      deps += invoker.base_deps
+    }
   }
 
   all_deps = []
   if (defined(invoker.deps)) {
     all_deps += invoker.deps
   }
 
   group("${target_name}__is_mojo_application_manifest") {
   }
 
   # Explicitly ensure that all dependencies are mojo_application_manifest
   # targets themselves.
   group("${target_name}__check_deps_are_all_mojo_application_manifest") {
     deps = []
     foreach(d, all_deps) {
       name = get_label_info(d, "label_no_toolchain")
       toolchain = get_label_info(d, "toolchain")
       deps += [ "${name}__is_mojo_application_manifest(${toolchain})" ]
     }
   }
 }