Make tab audible and muted states and cause available for an extension API

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 5ec31a02c05612ac3f3807e8b0e0ed9d560352f4..e57a48a4d772dce7a8bd7e85c6a23d902fe3a9ad 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -331,7 +331,8 @@ WebContentsImpl::WebContentsImpl(BrowserContext* browser_context,
       geolocation_service_context_(new GeolocationServiceContext()),
       accessibility_mode_(
           BrowserAccessibilityStateImpl::GetInstance()->accessibility_mode()),
-      audio_stream_monitor_(this),
+      audio_stream_monitor_(base::Bind(
+          &WebContentsImpl::NotifyAudibleStateChanged, base::Unretained(this))),
       loading_weak_factory_(this) {
   for (size_t i = 0; i < g_created_callbacks.Get().size(); i++)
     g_created_callbacks.Get().at(i).Run(this);
@@ -949,14 +950,16 @@ bool WebContentsImpl::IsAudioMuted() const {
   return audio_muter_.get() && audio_muter_->is_muting();
 }
 
-void WebContentsImpl::SetAudioMuted(bool mute) {
-  DVLOG(1) << "SetAudioMuted(mute=" << mute << "), was " << IsAudioMuted()
-           << " for WebContentsImpl@" << this;
+void WebContentsImpl::SetAudioMuted(bool muted, const std::string& cause) {
+  DVLOG(1) << "SetAudioMuted(muted=" << muted << ", cause =" << cause
+           << "), was " << IsAudioMuted() << " for WebContentsImpl@" << this;
 
-  if (mute == IsAudioMuted())
+  if (muted == IsAudioMuted())
     return;
 
-  if (mute) {
+  NotifyMutedStateChanged(muted, cause);
+
+  if (muted) {
     if (!audio_muter_)
       audio_muter_.reset(new WebContentsAudioMuter(this));
     audio_muter_->StartMuting();
@@ -995,20 +998,32 @@ bool WebContentsImpl::IsBeingDestroyed() const {
 
 void WebContentsImpl::NotifyNavigationStateChanged(
     InvalidateTypes changed_flags) {
+  if (delegate_)
+    delegate_->NavigationStateChanged(this, changed_flags);
+}
+
+void WebContentsImpl::NotifyAudibleStateChanged(bool is_audible) {
+  DCHECK(AudioStreamMonitor::monitoring_available());
+
   // Create and release the audio power save blocker depending on whether the
   // tab is actively producing audio or not.
-  if (changed_flags == INVALIDATE_TYPE_TAB &&
-      AudioStreamMonitor::monitoring_available()) {
-    if (WasRecentlyAudible()) {
-      if (!audio_power_save_blocker_)
-        CreateAudioPowerSaveBlocker();
-    } else {
-      audio_power_save_blocker_.reset();
-    }
+  if (WasRecentlyAudible()) {
+    if (!audio_power_save_blocker_)
+      CreateAudioPowerSaveBlocker();
+  } else {
+    audio_power_save_blocker_.reset();
   }
 
-  if (delegate_)
-    delegate_->NavigationStateChanged(this, changed_flags);
+  // Notify delegate that a UI update may be needed for new tab media state.
+  NotifyNavigationStateChanged(INVALIDATE_TYPE_TAB);
+
+  FOR_EACH_OBSERVER(WebContentsObserver, observers_, TabAudible(is_audible));
+}
+
+void WebContentsImpl::NotifyMutedStateChanged(
+    bool is_muted,
+    const std::string& cause) {
+  FOR_EACH_OBSERVER(WebContentsObserver, observers_, TabMuted(is_muted, cause));
 }
 
 base::TimeTicks WebContentsImpl::GetLastActiveTime() const {