Revert of Revert of 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..c2771307571c51d7bc3946e7ec8e77646e4c6346
--- /dev/null
+++ b/content/browser/android/media_players_observer.cc
@@ -0,0 +1,59 @@
+// 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) {
+  audio_status_map_.erase(Key(rfh, player_id));

[Tima Vaisburd, 2015/03/03 23:16:16]

The DCHECK was removed from here (see description).

+  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