Communicate audio state to renderer process on Android.

content/browser/media/media_web_contents_observer.cc

 // Copyright 2014 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.
 
 #include "content/browser/media/media_web_contents_observer.h"
 
 #include <memory>
 
 #include "base/lazy_instance.h"
 #include "build/build_config.h"
@@ skipping 25 matching lines @@
   g_audible_metrics.Get().UpdateAudibleWebContentsState(web_contents(), false);
 }
 
 void MediaWebContentsObserver::RenderFrameDeleted(
     RenderFrameHost* render_frame_host) {
   ClearPowerSaveBlockers(render_frame_host);
   session_controllers_manager_.RenderFrameDeleted(render_frame_host);
 }
 
 void MediaWebContentsObserver::MaybeUpdateAudibleState() {
-  if (!AudioStreamMonitor::monitoring_available())
+  if (!AudioStreamMonitor::power_level_monitoring_available())

[DaleCurtis, 2016/11/15 19:26:01]

I think this can be removed now as well as some of the other pieces below since
this code works on the same premise as what you've brought to the stream
monitor.

[altimin, 2016/11/16 12:52:46]

I'm a little hesitant about it — it is really a good idea to prevent Android
from entering power save mode when audio track is present? I'm afraid that we
will use more power and I'd like an explicit confirmation from someone who knows
what's happening here.

[DaleCurtis, 2016/11/16 22:16:51]

Sorry if I was unclear, there should be no behavioral change. If there is,
something is unexpected. The existing power save blocker should only be
configured when an audio stream is playing. Both implementations should now be
doing the same thing IIRC. Also I wrote all this, so I'm probably that someone
:)

[altimin, 2016/11/17 16:13:26]

Oh, I finally figured it out (previously I thought that power blocker was
enabled only on desktop).
Done.

     return;
 
   AudioStreamMonitor* audio_stream_monitor =
       static_cast<WebContentsImpl*>(web_contents())->audio_stream_monitor();
 
   if (audio_stream_monitor->WasRecentlyAudible()) {
     if (!audio_power_save_blocker_)
       CreateAudioPowerSaveBlocker();
   } else {
     audio_power_save_blocker_.reset();
@@ skipping 74 matching lines @@
   if (is_remote)
     return;
 
   const MediaPlayerId id(render_frame_host, delegate_id);
   if (has_audio) {
     AddMediaPlayerEntry(id, &active_audio_players_);
 
     // If we don't have audio stream monitoring, allocate the audio power save
     // blocker here instead of during NotifyNavigationStateChanged().
     if (!audio_power_save_blocker_ &&
-        !AudioStreamMonitor::monitoring_available()) {
+        !AudioStreamMonitor::power_level_monitoring_available()) {
       CreateAudioPowerSaveBlocker();
     }
   }
 
   if (has_video) {
     AddMediaPlayerEntry(id, &active_video_players_);
 
     // If we're not hidden and have just created a player, create a blocker.
     if (!video_power_save_blocker_ &&
         !static_cast<WebContentsImpl*>(web_contents())->IsHidden()) {
@@ skipping 49 matching lines @@
         web_contents()->GetNativeView());
   }
 #endif
 }
 
 void MediaWebContentsObserver::MaybeReleasePowerSaveBlockers() {
   // If there are no more audio players and we don't have audio stream
   // monitoring, release the audio power save blocker here instead of during
   // NotifyNavigationStateChanged().
   if (active_audio_players_.empty() &&
-      !AudioStreamMonitor::monitoring_available()) {
+      !AudioStreamMonitor::power_level_monitoring_available()) {
     audio_power_save_blocker_.reset();
   }
 
   // If there are no more video players, clear the video power save blocker.
   if (active_video_players_.empty())
     video_power_save_blocker_.reset();
 }
 
 void MediaWebContentsObserver::AddMediaPlayerEntry(
     const MediaPlayerId& id,
@@ skipping 28 matching lines @@
   if (it == player_map->end())
     return;
 
   for (int delegate_id : it->second)
     removed_players->insert(MediaPlayerId(render_frame_host, delegate_id));
 
   player_map->erase(it);
 }
 
 }  // namespace content