Reland of [Background Sync] Trigger Background Sync events when Chrome is backgrounded on Android

content/content_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.
 
 {
   'dependencies': [
     '../base/base.gyp:base_static',
     '../components/url_formatter/url_formatter.gyp:url_formatter',
     '../crypto/crypto.gyp:crypto',
     '../device/battery/battery.gyp:device_battery',
@@ skipping 328 matching lines @@
       'browser/accessibility/browser_accessibility_state_impl.cc',
       'browser/accessibility/browser_accessibility_state_impl.h',
       'browser/accessibility/browser_accessibility_state_impl_win.cc',
       'browser/accessibility/browser_accessibility_win.cc',
       'browser/accessibility/browser_accessibility_win.h',
       'browser/accessibility/one_shot_accessibility_tree_search.cc',
       'browser/accessibility/one_shot_accessibility_tree_search.h',
       'browser/android/animation_utils.h',
       'browser/android/background_sync_launcher_android.cc',
       'browser/android/background_sync_launcher_android.h',
+      'browser/android/background_sync_network_observer_android.cc',
+      'browser/android/background_sync_network_observer_android.h',
       'browser/android/browser_jni_registrar.cc',
       'browser/android/browser_jni_registrar.h',
       'browser/android/browser_startup_controller.cc',
       'browser/android/browser_startup_controller.h',
       'browser/android/browser_surface_texture_manager.cc',
       'browser/android/browser_surface_texture_manager.h',
       'browser/android/child_process_launcher_android.cc',
       'browser/android/child_process_launcher_android.h',
       'browser/android/composited_touch_handle_drawable.cc',
       'browser/android/composited_touch_handle_drawable.h',
@@ skipping 1829 matching lines @@
     ['enable_webvr==1 and OS=="android"', {
       'sources': [
         'browser/vr/android/cardboard/cardboard_vr_device.cc',
         'browser/vr/android/cardboard/cardboard_vr_device.h',
         'browser/vr/android/cardboard/cardboard_vr_device_provider.cc',
         'browser/vr/android/cardboard/cardboard_vr_device_provider.h',
       ],
     }],
   ],
 }