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

content/browser/web_contents/web_contents_impl.cc

 // 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.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 313 matching lines @@
       currentPinchZoomStepDelta_(0),
       render_view_message_source_(NULL),
       fullscreen_widget_routing_id_(MSG_ROUTING_NONE),
       fullscreen_widget_had_focus_at_shutdown_(false),
       is_subframe_(false),
       force_disable_overscroll_content_(false),
       last_dialog_suppressed_(false),
       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);
   frame_tree_.SetFrameRemoveListener(
       base::Bind(&WebContentsImpl::OnFrameRemoved,
                  base::Unretained(this)));
 }
 
 WebContentsImpl::~WebContentsImpl() {
   is_being_destroyed_ = true;
@@ skipping 597 matching lines @@
 }
 
 int WebContentsImpl::GetCapturerCount() const {
   return capturer_count_;
 }
 
 bool WebContentsImpl::IsAudioMuted() const {
   return audio_muter_.get() && audio_muter_->is_muting();
 }
 
-void WebContentsImpl::SetAudioMuted(bool mute) {
-  DVLOG(1) << "SetAudioMuted(mute=" << mute << "), was " << IsAudioMuted()
+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();
   } else {
     DCHECK(audio_muter_);
     audio_muter_->StopMuting();
   }
 
   // Notification for UI updates in response to the changed muting state.
   NotifyNavigationStateChanged(INVALIDATE_TYPE_TAB);
@@ skipping 18 matching lines @@
 base::TerminationStatus WebContentsImpl::GetCrashedStatus() const {
   return crashed_status_;
 }
 
 bool WebContentsImpl::IsBeingDestroyed() const {
   return is_being_destroyed_;
 }
 
 void WebContentsImpl::NotifyNavigationStateChanged(
     InvalidateTypes changed_flags) {
-  // 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 (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 (WasRecentlyAudible()) {
+    if (!audio_power_save_blocker_)
+      CreateAudioPowerSaveBlocker();
+  } else {
+    audio_power_save_blocker_.reset();
+  }
+
+  // TODO: The following should be eliminated once the browser UI uses the new WebContentsObserver interface.

[miu, 2014/12/05 23:46:48]

Actually, I think I gave you bad advice (earlier) on having this TODO comment
here.  I need to first discuss this issue with the browser UI owners some more,
to decide whether NotifyNavigationStateChanged() is the right or wrong mechanism
to update the tab strip UI.  (Maybe the mechanism is right, and the method
should just be renamed to something better.)

In other words, for now, please replace this TODO comment with:

  // Notify the delegate that a UI update may be needed for the 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 {
   return last_active_time_;
 }
 
 void WebContentsImpl::WasShown() {
   controller_.SetActive(true);
 
   std::set<RenderWidgetHostView*> widgets = GetRenderWidgetHostViewsInTree();
   for (std::set<RenderWidgetHostView*>::iterator iter = widgets.begin();
        iter != widgets.end();
@@ skipping 3324 matching lines @@
   node->render_manager()->ResumeResponseDeferredAtStart();
 }
 
 void WebContentsImpl::SetForceDisableOverscrollContent(bool force_disable) {
   force_disable_overscroll_content_ = force_disable;
   if (view_)
     view_->SetOverscrollControllerEnabled(CanOverscrollContent());
 }
 
 }  // namespace content