Add a non-blocking "OneShotEvent" class

chrome/chrome_common.gypi

 # Copyright (c) 2013 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': 'common',
       'type': 'static_library',
       'variables': {
@@ skipping 35 matching lines @@
         '<(DEPTH)/third_party/icu/icu.gyp:icuuc',
         '<(DEPTH)/third_party/libxml/libxml.gyp:libxml',
         '<(DEPTH)/third_party/mt19937ar/mt19937ar.gyp:mt19937ar',
         '<(DEPTH)/third_party/sqlite/sqlite.gyp:sqlite',
         '<(DEPTH)/third_party/zlib/zlib.gyp:zip',
         '<(DEPTH)/ui/ui.gyp:ui_resources',
         '<(DEPTH)/webkit/support/webkit_support.gyp:user_agent',
       ],
       'sources': [
         '../apps/app_shim/app_shim_messages.h',
+        '../extensions/common/async_event.cc',
+        '../extensions/common/async_event.h',
         '../extensions/common/constants.cc',
         '../extensions/common/constants.h',
         '../extensions/common/crx_file.cc',
         '../extensions/common/crx_file.h',
         '../extensions/common/draggable_region.cc',
         '../extensions/common/draggable_region.h',
         '../extensions/common/error_utils.cc',
         '../extensions/common/error_utils.h',
         '../extensions/common/event_filter.cc',
         '../extensions/common/event_filter.h',
@@ skipping 686 matching lines @@
         'common/metrics/proto/user_action_event.proto',
       ],
       'variables': {
         'proto_in_dir': 'common/metrics/proto',
         'proto_out_dir': 'chrome/common/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }