Add a method to tab_utils.h to find out whether a tab is playing audio.

chrome/chrome_browser.gypi

 # Copyright 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',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 983 matching lines @@
         'browser/managed_mode/managed_mode_interstitial.cc',
         'browser/managed_mode/managed_mode_interstitial.h',
         'browser/managed_mode/managed_mode_navigation_observer.cc',
         'browser/managed_mode/managed_mode_navigation_observer.h',
         'browser/managed_mode/managed_mode_resource_throttle.cc',
         'browser/managed_mode/managed_mode_resource_throttle.h',
         'browser/managed_mode/managed_mode_site_list.cc',
         'browser/managed_mode/managed_mode_site_list.h',
         'browser/managed_mode/managed_mode_url_filter.cc',
         'browser/managed_mode/managed_mode_url_filter.h',
+        'browser/media/audio_stream_indicator.cc',
+        'browser/media/audio_stream_indicator.h',
         'browser/media/media_capture_devices_dispatcher.cc',
         'browser/media/media_capture_devices_dispatcher.h',
         'browser/media/media_internals.cc',
         'browser/media/media_internals.h',
         'browser/media/media_stream_capture_indicator.cc',
         'browser/media/media_stream_capture_indicator.h',
         'browser/media/media_stream_devices_controller.cc',
         'browser/media/media_stream_devices_controller.h',
         'browser/media_gallery/linux/mtp_device_delegate_impl_linux.cc',
         'browser/media_gallery/linux/mtp_device_delegate_impl_linux.h',
@@ skipping 2095 matching lines @@
             'proto_in_dir': '../third_party/cros_system_api/dbus',
             'proto_out_dir': 'chrome/browser/media_transfer_protocol',
           },
           'includes': ['../build/protoc.gypi'],
         },
       ],
      },
     ],
   ],
 }