Fix a bunch of generated file build flakes in //extensions

extensions/common/api/schema.gni

-# Copyright 2014 The Chromium Authors. All rights reserved.
+# 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.
 
-import("//build/config/features.gni")
-import("//build/json_schema_api.gni")
-import("//mojo/public/tools/bindings/mojom.gni")
-
-assert(enable_extensions)
-
-schema_files = [
+extensions_api_schema_files_ = [
   "alarms.idl",
   "app_current_window_internal.idl",
   "app_runtime.idl",
   "app_view_guest_internal.json",
   "app_window.idl",
   "audio.idl",
   "bluetooth.idl",
   "bluetooth_low_energy.idl",
   "bluetooth_private.idl",
   "bluetooth_socket.idl",
@@ skipping 32 matching lines @@
   "system_network.idl",
   "system_storage.idl",
   "test.json",
   "usb.idl",
   "virtual_keyboard_private.json",
   "web_request.json",
   "web_view_internal.json",
 ]
 
 if (is_chromeos) {
-  schema_files += [
+  extensions_api_schema_files_ += [
     "diagnostics.idl",
     "networking_config.idl",
     "vpn_provider.idl",
     "webcam_private.idl",
   ]
 }
 
-uncompiled_sources = [ "web_request_internal.json" ]
+extensions_api_schema_files =
+    get_path_info(extensions_api_schema_files_, "abspath")
 
-uncompiled_bundle_schema_sources = [
-  "declarative_web_request.json",
-  "web_view_request.json",
-]
+extensions_api_uncompiled_sources =
+    get_path_info([ "web_request_internal.json" ], "abspath")
 
-root_namespace = "extensions::api::%(namespace)s"
+extensions_api_uncompiled_bundle_schema_sources =
+    get_path_info([
+                    "declarative_web_request.json",
+                    "web_view_request.json",
+                  ],
+                  "abspath")
 
-json_schema_api("generated_api") {
-  sources = schema_files
-  schemas = true
-  bundle = true
-  bundle_name = ""
-
-  # Inherit uncompiled_sources, uncompiled_bundle_schema_sources, and
-  # root_namespace.
-}
-
-mojom("mojom") {
-  sources = [
-    "mime_handler.mojom",
-  ]
-
-  use_new_wrapper_types = false
-}
-
-group("api") {
-  public_deps = [
-    ":generated_api",
-    ":mojom",
-  ]
-}
-
-json_schema_api("api_registration") {
-  sources = schema_files
-  impl_dir = "//extensions/browser/api"
-  bundle_registration = true
-  bundle_name = ""
-
-  deps = [
-    ":api",
-    "//device/serial",
-    "//extensions/common/api/cast_channel:cast_channel_proto",
-    "//skia",
-  ]
-
-  # Inherit uncompiled_sources, uncompiled_bundle_schema_sources, and
-  # root_namespace.
-}
+extensions_api_root_namespace = "extensions::api::%(namespace)s"