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..6a9c6da6df27d9cb705af108bf57672adac3ac14 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -125,6 +125,10 @@ const double kMinimumLoadingProgress = 0.1;
 
 const char kDotGoogleDotCom[] = ".google.com";
 
+// String to indicate that muted state change is initial
+// (instead of by user, tab capture, or an extension id).
+const char kMutedToggleCauseInit[] = "initial";
+
 #if defined(OS_ANDROID)
 const char kWebContentsAndroidKey[] = "web_contents_android";
 #endif  // OS_ANDROID
@@ -310,6 +314,7 @@ WebContentsImpl::WebContentsImpl(BrowserContext* browser_context,
       upload_position_(0),
       displayed_insecure_content_(false),
       has_accessed_initial_document_(false),
+      mutedToggleCause_(kMutedToggleCauseInit),
       capturer_count_(0),
       should_normally_be_visible_(true),
       is_being_destroyed_(false),
@@ -949,14 +954,16 @@ 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) {
+  mutedToggleCause_ = cause;
+
+  if (muted) {
     if (!audio_muter_)
       audio_muter_.reset(new WebContentsAudioMuter(this));
     audio_muter_->StartMuting();
@@ -969,6 +976,10 @@ void WebContentsImpl::SetAudioMuted(bool mute) {
   NotifyNavigationStateChanged(INVALIDATE_TYPE_TAB);
 }
 
+const std::string& WebContentsImpl::GetAudioMutedCause() const {
+  return mutedToggleCause_;
+}
+
 bool WebContentsImpl::IsCrashed() const {
   return (crashed_status_ == base::TERMINATION_STATUS_PROCESS_CRASHED ||
           crashed_status_ == base::TERMINATION_STATUS_ABNORMAL_TERMINATION ||