Make BrowserMainParts have an empty implementation to make embedding easier.

chrome/chrome_browser.gypi

 # Copyright (c) 2012 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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
@@ skipping 349 matching lines @@
         'browser/certificate_viewer.cc',
         'browser/certificate_viewer.h',
         'browser/character_encoding.cc',
         'browser/character_encoding.h',
         'browser/chrome_benchmarking_message_filter.cc',
         'browser/chrome_benchmarking_message_filter.h',
         'browser/chrome_browser_application_mac.h',
         'browser/chrome_browser_application_mac.mm',
         'browser/chrome_browser_main.cc',
         'browser/chrome_browser_main.h',
-        'browser/chrome_browser_main_extra_parts.cc',
         'browser/chrome_browser_main_extra_parts.h',
         'browser/chrome_browser_main_linux.cc',
         'browser/chrome_browser_main_linux.h',
         'browser/chrome_browser_main_mac.h',
         'browser/chrome_browser_main_mac.mm',
         'browser/chrome_browser_main_posix.cc',
         'browser/chrome_browser_main_posix.h',
         'browser/chrome_browser_main_win.cc',
         'browser/chrome_browser_main_win.h',
         'browser/chrome_browser_main_x11.cc',
@@ skipping 4740 matching lines @@
         'browser/metrics/proto/study.proto',
       ],
       'variables': {
         'proto_in_dir': 'browser/metrics/proto',
         'proto_out_dir': 'chrome/browser/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }