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

content/browser/media/capture/web_contents_audio_input_stream.cc

 // Copyright (c) 2013 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/capture/web_contents_audio_input_stream.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "content/browser/media/capture/audio_mirroring_manager.h"
 #include "content/browser/media/capture/web_contents_capture_util.h"
 #include "content/browser/media/capture/web_contents_tracker.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/web_contents.h"
 #include "media/audio/virtual_audio_input_stream.h"
 #include "media/audio/virtual_audio_output_stream.h"
 #include "media/base/bind_to_current_loop.h"
 
 namespace content {
 
+// String to indicate that muted state change was caused by capture
+// (instead of initial, user or an extension id).
+static const char kMutedToggleCauseCapture[] = "auto-forced for capture";
+
 class WebContentsAudioInputStream::Impl
     : public base::RefCountedThreadSafe<WebContentsAudioInputStream::Impl>,
       public AudioMirroringManager::MirroringDestination {
  public:
   // Takes ownership of |mixer_stream|.  The rest outlive this instance.
   Impl(int render_process_id, int main_render_frame_id,
        AudioMirroringManager* mirroring_manager,
        const scoped_refptr<WebContentsTracker>& tracker,
        media::VirtualAudioInputStream* mixer_stream);
 
@@ skipping 208 matching lines @@
       base::Bind(&AudioMirroringManager::StopMirroring,
                  base::Unretained(mirroring_manager_),
                  make_scoped_refptr(this)));
 }
 
 void WebContentsAudioInputStream::Impl::UnmuteWebContentsAudio() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   WebContents* const contents = tracker_->web_contents();
   if (contents)
-    contents->SetAudioMuted(false);
+    contents->SetAudioMuted(false, kMutedToggleCauseCapture);
 }
 
 void WebContentsAudioInputStream::Impl::QueryForMatches(
     const std::set<SourceFrameRef>& candidates,
     const MatchesCallback& results_callback) {
   BrowserThread::PostTask(
       BrowserThread::UI,
       FROM_HERE,
       base::Bind(&Impl::QueryForMatchesOnUIThread,
                  this,
@@ skipping 123 matching lines @@
 
 bool WebContentsAudioInputStream::GetAutomaticGainControl() {
   return impl_->mixer_stream()->GetAutomaticGainControl();
 }
 
 bool WebContentsAudioInputStream::IsMuted() {
   return false;
 }
 
 }  // namespace content