Implement a salt for MediaSource IDs that can be cleared by a user.

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': [
     'browser/speech/proto/speech_proto.gyp:speech_proto',
     '../base/base.gyp:base_static',
     '../crypto/crypto.gyp:crypto',
     '../google_apis/google_apis.gyp:google_apis',
@@ skipping 683 matching lines @@
     'browser/mach_broker_mac.h',
     'browser/mach_broker_mac.mm',
     'browser/media/android/browser_demuxer_android.cc',
     'browser/media/android/browser_demuxer_android.h',
     'browser/media/android/browser_media_player_manager.cc',
     'browser/media/android/browser_media_player_manager.h',
     'browser/media/android/media_drm_credential_manager.cc',
     'browser/media/android/media_drm_credential_manager.h',
     'browser/media/android/media_resource_getter_impl.cc',
     'browser/media/android/media_resource_getter_impl.h',
+    'browser/media/media_devices_monitor.cc',
     'browser/media/media_internals.cc',
     'browser/media/media_internals.h',
     'browser/media/media_internals_handler.cc',
     'browser/media/media_internals_handler.h',
     'browser/media/media_internals_proxy.cc',
     'browser/media/media_internals_proxy.h',
     'browser/media/media_internals_ui.cc',
     'browser/media/media_internals_ui.h',
     'browser/media/webrtc_identity_store.cc',
     'browser/media/webrtc_identity_store.h',
     'browser/media/webrtc_identity_store_backend.cc',
     'browser/media/webrtc_identity_store_backend.h',
     'browser/media/webrtc_internals.cc',
     'browser/media/webrtc_internals.h',
     'browser/media/webrtc_internals_message_handler.cc',
     'browser/media/webrtc_internals_message_handler.h',
     'browser/media/webrtc_internals_ui.cc',
     'browser/media/webrtc_internals_ui.h',
     'browser/media/webrtc_internals_ui_observer.h',
-    'browser/media_devices_monitor.cc',
     'browser/message_port_message_filter.cc',
     'browser/message_port_message_filter.h',
     'browser/message_port_service.cc',
     'browser/message_port_service.h',
     'browser/mime_registry_message_filter.cc',
     'browser/mime_registry_message_filter.h',
     'browser/service_worker/service_worker_dispatcher_host.h',
     'browser/service_worker/service_worker_dispatcher_host.cc',
     'browser/service_worker/service_worker_context.h',
     'browser/service_worker/service_worker_context.cc',
@@ skipping 823 matching lines @@
         ['exclude', '^browser/speech/input_tag_speech_dispatcher_host\\.(cc|h)$'],
       ],
     }, {  # input_speech==1
       'dependencies': [
         '../third_party/flac/flac.gyp:libflac',
         '../third_party/speex/speex.gyp:libspeex',
       ],
     }],
   ],
 }