Propagate audible state from player to the containing tab

content/browser/android/audio_monitor_android.h

+// Copyright 2015 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.
+
+#ifndef CONTENT_BROWSER_ANDROID_AUDIO_MONITOR_ANDROID_H_
+#define CONTENT_BROWSER_ANDROID_AUDIO_MONITOR_ANDROID_H_
+
+#include <map>
+#include "base/macros.h"
+
+namespace content {
+
+class WebContents;
+class RenderFrameHost;
+
+// This class maintains the audible state of many players

[no sievers, 2015/02/10 01:33:03]

You should say that this class is associated with a WebContents, and maintains
the state regarding all the players in there.

[Tima Vaisburd, 2015/02/11 03:34:05]

Changed the wording, please verify.

+// together. That state is accociated with a WebContents that might have
+// several players.
+// The audible state is true if at least one player is playing a sound.
+// Whenever the audible state of the WebContents as a whole changes, this
+// class sends notification to it.
+class AudioMonitorAndroid {
+ public:
+  // Constructor, web_contents represents the tab.

[no sievers, 2015/02/10 01:33:03]

Let's avoid talking about 'tabs' here and below which is not a concept in
content/. This is associated with a WebContents.

[Tima Vaisburd, 2015/02/11 03:34:05]

Done.

+  explicit AudioMonitorAndroid(WebContents* web_contents);
+  ~AudioMonitorAndroid();
+
+  // Returns the audible state of the whole tab.
+  bool is_audible() const { return is_audible_; }
+
+  // These methods constitute the observer pattern, should
+  // be called when corresponding event happens. They will notify
+  // WebContents whenever the whole tab audible state changes.
+  void OnAudibleStateChanged(RenderFrameHost* rfh, int player_id,
+                             bool is_audible);
+  void RemovePlayer(RenderFrameHost* rfh, int player_id);
+  void RenderFrameDeleted(RenderFrameHost* rfh);
+
+ private:
+  void UpdateStatusAndNotify();
+
+  // Contents of the tab this monitor is associated with
+  WebContents* web_contents_;
+
+  // Audible status per player ID and frame
+  typedef std::pair<RenderFrameHost*, int> Key;
+  typedef std::map<Key, bool> StatusMap;
+  StatusMap audio_status_map_;
+
+  // The audible state of the whole tab
+  bool is_audible_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioMonitorAndroid);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ANDROID_AUDIO_MONITOR_ANDROID_H_