components: Introduce AlarmTimer class and use it for GCM heartbeat

components/components.gyp

 # 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.
 
 {
   'variables': {
     # This turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
@@ skipping 71 matching lines @@
     ['OS != "ios" and OS != "android"', {
       'includes': [
         'copresence.gypi',
         'proximity_auth.gypi',
         'storage_monitor.gypi',
       ]
     }],
     ['chromeos == 1', {
       'includes': [
         'pairing.gypi',
+        'timers.gypi',
       ],
     }],
     ['OS == "win" or OS == "mac"', {
       'includes': [
         'wifi.gypi',
       ],
     }],
     ['use_ash==1', {
       'includes': [
         'session_manager.gypi',
@@ skipping 12 matching lines @@
         'invalidation.gypi',
       ],
     }],
     ['enable_plugins==1', {
       'includes': [
         'pdf.gypi',
       ],
     }],
   ],
 }