Have content/ create and destroy its own threads.

content/content_browser.gypi

 # Copyright (c) 2011 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.
 
 {
   'dependencies': [
     '../crypto/crypto.gyp:crypto',
     '../net/net.gyp:net',
     '../net/net.gyp:http_server',
     '../ppapi/ppapi_internal.gyp:ppapi_proxy',
     '../skia/skia.gyp:skia',
     '../third_party/flac/flac.gyp:libflac',
     # TODO(ericu): remove leveldb ref after crbug.com/6955013 is fixed.
     '../third_party/leveldatabase/leveldatabase.gyp:leveldatabase',
     '../third_party/speex/speex.gyp:libspeex',
     '../third_party/WebKit/Source/WebKit/chromium/WebKit.gyp:webkit',
     '../third_party/zlib/zlib.gyp:zlib',
     '../ui/ui.gyp:ui',
     '../ui/ui.gyp:ui_resources',
     '../webkit/support/webkit_support.gyp:webkit_resources',
     '../webkit/support/webkit_support.gyp:webkit_strings',
   ],
   'include_dirs': [
     '..',
     '<(INTERMEDIATE_DIR)',
   ],
   'sources': [
     'public/browser/browser_main_parts.h',
+    'public/browser/browser_shutdown.h',
     'public/browser/browser_thread.h',
     'public/browser/content_browser_client.h',
     'public/browser/content_ipc_logging.h',
     'public/browser/download_manager_delegate.h',
     'public/browser/native_web_keyboard_event.h',
     'public/browser/navigation_types.h',
     'public/browser/notification_details.h',
     'public/browser/notification_observer.h',
     'public/browser/notification_registrar.cc',
     'public/browser/notification_registrar.h',
@@ skipping 754 matching lines @@
         'browser/renderer_host/java/java_bridge_dispatcher_host_manager.h',
         'browser/renderer_host/java/java_bridge_dispatcher_host.cc',
         'browser/renderer_host/java/java_bridge_dispatcher_host.h',
         'browser/renderer_host/java/java_method.cc',
         'browser/renderer_host/java/java_method.h',
       ],
     }],
   ],
 }