Propagate audible state from player to the containing tab

content/browser/android/media_players_observer.cc

Index: content/browser/android/media_players_observer.cc
diff --git a/content/browser/android/media_players_observer.cc b/content/browser/android/media_players_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c4fd4727873b4c28f59410920f6d3756d62463df
--- /dev/null
+++ b/content/browser/android/media_players_observer.cc
@@ -0,0 +1,60 @@
+// 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.
+
+#include "content/browser/android/media_players_observer.h"
+
+#include <climits>
+
+#include "base/logging.h"
+#include "content/public/browser/web_contents.h"
+
+namespace content {
+
+MediaPlayersObserver::MediaPlayersObserver(WebContents* web_contents)
+    : AudioStateProvider(web_contents) {
+}
+
+MediaPlayersObserver::~MediaPlayersObserver() {}
+
+bool MediaPlayersObserver::IsAudioStateAvailable() const {
+  return true;
+}
+
+// This audio state provider does not have a monitor
+AudioStreamMonitor* MediaPlayersObserver::audio_stream_monitor() {
+  return nullptr;
+}
+
+void MediaPlayersObserver::OnAudibleStateChanged(RenderFrameHost* rfh,
+                                                int player_id,
+                                                bool is_audible) {
+  audio_status_map_[Key(rfh, player_id)] = is_audible;
+  UpdateStatusAndNotify();
+}
+
+void MediaPlayersObserver::RemovePlayer(RenderFrameHost* rfh, int player_id) {
+  size_t num_erased_entries = audio_status_map_.erase(Key(rfh, player_id));
+  DCHECK_EQ(1u, num_erased_entries);
+  UpdateStatusAndNotify();
+}
+
+void MediaPlayersObserver::RenderFrameDeleted(RenderFrameHost* rfh) {
+  StatusMap::iterator begin = audio_status_map_.lower_bound(Key(rfh, 0));
+  StatusMap::iterator end = audio_status_map_.upper_bound(Key(rfh, INT_MAX));
+  audio_status_map_.erase(begin, end);
+  UpdateStatusAndNotify();
+}
+
+void MediaPlayersObserver::UpdateStatusAndNotify() {
+  for (const auto& player_status : audio_status_map_) {
+    if (player_status.second) {
+      Notify(true);  // at least one player is making noise
+      return;
+    }
+  }
+
+  Notify(false);
+}
+
+} // namespace content