Communicate audio state to renderer process on Android.

content/browser/media/audio_stream_monitor.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/audio_stream_monitor.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 13 matching lines @@
 
   return web_contents ? web_contents->audio_stream_monitor() : nullptr;
 }
 
 }  // namespace
 
 AudioStreamMonitor::AudioStreamMonitor(WebContents* contents)
     : web_contents_(contents),
       clock_(&default_tick_clock_),
       was_recently_audible_(false),
-      is_audible_(false)
-{
+      is_audible_(false),
+      active_streams_(0) {
   DCHECK(web_contents_);
 }
 
 AudioStreamMonitor::~AudioStreamMonitor() {}
 
 bool AudioStreamMonitor::WasRecentlyAudible() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return was_recently_audible_;
 }
 
 bool AudioStreamMonitor::IsCurrentlyAudible() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return is_audible_;
 }
 
 // static
 void AudioStreamMonitor::StartMonitoringStream(
     int render_process_id,
     int render_frame_id,
     int stream_id,
     const ReadPowerAndClipCallback& read_power_callback) {
-  if (!monitoring_available())
-    return;
   BrowserThread::PostTask(BrowserThread::UI,
                           FROM_HERE,
                           base::Bind(&StartMonitoringHelper,
                                      render_process_id,
                                      render_frame_id,
                                      stream_id,
                                      read_power_callback));
 }
 
 // static
 void AudioStreamMonitor::StopMonitoringStream(int render_process_id,
                                               int render_frame_id,
                                               int stream_id) {
-  if (!media::AudioOutputController::will_monitor_audio_levels())
-    return;
   BrowserThread::PostTask(BrowserThread::UI,
                           FROM_HERE,
                           base::Bind(&StopMonitoringHelper,
                                      render_process_id,
                                      render_frame_id,
                                      stream_id));
 }
 
 // static
 void AudioStreamMonitor::StartMonitoringHelper(
     int render_process_id,
     int render_frame_id,
     int stream_id,
     const ReadPowerAndClipCallback& read_power_callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   AudioStreamMonitor* const monitor =
       AudioStreamMonitorFromRenderFrame(render_process_id, render_frame_id);
-  if (monitor) {
-    monitor->StartMonitoringStreamOnUIThread(
-        render_process_id, stream_id, read_power_callback);
-  }
+  if (!monitor)
+    return;
+
+  monitor->OnStreamAdded();
+
+  if (!power_level_monitoring_available())
+    return;
+
+  monitor->StartMonitoringStreamOnUIThread(render_process_id, stream_id,
+                                           read_power_callback);
 }
 
 // static
 void AudioStreamMonitor::StopMonitoringHelper(int render_process_id,
                                               int render_frame_id,
                                               int stream_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   AudioStreamMonitor* const monitor =
       AudioStreamMonitorFromRenderFrame(render_process_id, render_frame_id);
-  if (monitor)
-    monitor->StopMonitoringStreamOnUIThread(render_process_id, stream_id);
+  if (!monitor)
+    return;
+
+  monitor->OnStreamRemoved();
+
+  if (!power_level_monitoring_available())
+    return;
+
+  monitor->StopMonitoringStreamOnUIThread(render_process_id, stream_id);
 }
 
 void AudioStreamMonitor::StartMonitoringStreamOnUIThread(
     int render_process_id,
     int stream_id,
     const ReadPowerAndClipCallback& read_power_callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(!read_power_callback.is_null());
   poll_callbacks_[StreamID(render_process_id, stream_id)] = read_power_callback;
   if (!poll_timer_.IsRunning()) {
@@ skipping 53 matching lines @@
   if (!should_indicator_be_on) {
     off_timer_.Stop();
   } else if (!off_timer_.IsRunning()) {
     off_timer_.Start(
         FROM_HERE,
         off_time - now,
         base::Bind(&AudioStreamMonitor::MaybeToggle, base::Unretained(this)));
   }
 }
 
+void AudioStreamMonitor::OnStreamAdded() {
+  ++active_streams_;

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

DCHECK_CURRENTLY_ON() ?

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

Done.

+
+  if (power_level_monitoring_available())
+    return;
+
+  if (active_streams_ == 1) {
+    is_audible_ = true;
+    web_contents_->OnAudioStateChanged(true);
+    MaybeToggle();
+  }
+}
+
+void AudioStreamMonitor::OnStreamRemoved() {
+  --active_streams_;
+
+  if (power_level_monitoring_available())
+    return;
+
+  if (active_streams_ == 0) {
+    is_audible_ = false;
+    web_contents_->OnAudioStateChanged(false);
+    MaybeToggle();
+  }
+}
+
 }  // namespace content