Use mojo volume interfaces for mash and classic ash.

chrome/browser/chromeos/extensions/extension_volume_observer.cc

Index: chrome/browser/chromeos/extensions/extension_volume_observer.cc
diff --git a/chrome/browser/chromeos/extensions/extension_volume_observer.cc b/chrome/browser/chromeos/extensions/extension_volume_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..845e76acdca3a2da0ee2ddee730291360ec832f2
--- /dev/null
+++ b/chrome/browser/chromeos/extensions/extension_volume_observer.cc
@@ -0,0 +1,42 @@
+// Copyright 2016 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 "chrome/browser/chromeos/extensions/extension_volume_observer.h"
+
+#include "chrome/browser/extensions/api/system_private/system_private_api.h"
+#include "chromeos/audio/cras_audio_handler.h"
+
+namespace chromeos {
+
+namespace {
+
+// A helper to call the corresponding extensions method.
+void DispatchVolumeChangedEvent() {
+  CrasAudioHandler* audio_handler = CrasAudioHandler::Get();
+  extensions::DispatchVolumeChangedEvent(
+      audio_handler->GetOutputVolumePercent(), audio_handler->IsOutputMuted());
+}
+
+}  // namespace
+
+ExtensionVolumeObserver::ExtensionVolumeObserver() {
+  CrasAudioHandler::Get()->AddAudioObserver(this);
+}
+
+ExtensionVolumeObserver::~ExtensionVolumeObserver() {
+  if (CrasAudioHandler::IsInitialized())
+    CrasAudioHandler::Get()->RemoveAudioObserver(this);
+}
+
+void ExtensionVolumeObserver::OnOutputNodeVolumeChanged(uint64_t node_id,
+                                                        int volume) {
+  DispatchVolumeChangedEvent();
+}
+
+void ExtensionVolumeObserver::OnOutputMuteChanged(bool /* mute_on */,
+                                                  bool /* system_adjust */) {
+  DispatchVolumeChangedEvent();
+}
+
+}  // namespace chromeos