Split bundle generation steps so that API registration is generated in browser, not common.

extensions/common/api/schemas.gypi

+# Copyright 2014 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.
+
+{
+  'sources': [
+    '<@(schema_files)',
+  ],
+  'variables': {
+    'chromium_code': 1,
+    # TODO: Eliminate these on Android. See crbug.com/305852.
+    'android_schema_files': [
+      'runtime.json',
+    ],
+    'main_schema_files': [
+      'app_runtime.idl',
+      'app_view_internal.json',
+      'cast_channel.idl',
+      'dns.idl',
+      'extensions_manifest_types.json',
+      'hid.idl',
+      'power.idl',
+      'runtime.json',
+      'serial.idl',
+      'socket.idl',
+      'sockets_tcp.idl',
+      'sockets_tcp_server.idl',
+      'sockets_udp.idl',
+      'storage.json',
+      'test.json',
+      'usb.idl',
+      'usb_private.idl',
+    ],
+    'non_compiled_schema_files': [
+    ],
+    'conditions': [
+      ['enable_extensions==1', {
+        'schema_files': [
+          '<@(main_schema_files)',
+        ],
+      }, {
+        'schema_files': [
+          '<@(android_schema_files)',
+        ],
+      }],
+    ],
+    'cc_dir': 'extensions/common/api',
+    'root_namespace': 'extensions::core_api::%(namespace)s',
+    'impl_dir_': 'extensions/browser/api',

[scottmg, 2014/08/25 17:09:01]

I think this or the target it's included into needs an msvs_external_rule:1. I'm
getting this on a full build:

[7163->26/7222 ~33] IDL ..\..\extensions\common\api\app_runtime.idl
FAILED: d:\src\depot_tools\python276_bin\python.exe gyp-win-tool midl-wrapper
environment.x86 obj\extensions\browser\api\extensions_api_registration.gen
app_runtime.tlb app_runtime.h app_runtime.dlldata.c app_runtime_i.c
app_runtime_p.c ..\..\extensions\common\api\app_runtime.idl /char signed /env
win32 /Oicf
..\..\extensions\common\api\app_runtime.idl(8) : error MIDL2025 : syntax error :
expecting an interface name or DispatchInterfaceName or CoclassName or
ModuleName or LibraryName or ContractName or a type specification near
"namespace"
..\..\extensions\common\api\app_runtime.idl(8) : error MIDL2026 : cannot recover
from earlier syntax errors; aborting compilation

+  },
+  'conditions': [
+    ['enable_extensions==1', {
+      'dependencies': [
+        '<(DEPTH)/device/serial/serial.gyp:device_serial',
+        '<(DEPTH)/skia/skia.gyp:skia',
+      ],
+    }],
+  ],
+}