Use mojo volume interfaces for mash and classic ash.

chrome/browser/chromeos/extensions/extension_system_event_observer.cc

Index: chrome/browser/chromeos/extensions/extension_system_event_observer.cc
diff --git a/chrome/browser/chromeos/extensions/extension_system_event_observer.cc b/chrome/browser/chromeos/extensions/extension_system_event_observer.cc
index 3938d9c7a72beae4584cd334469ea2bd3c9080f6..af3eb763838c7c4aea872bc4235e461878c19883 100644
--- a/chrome/browser/chromeos/extensions/extension_system_event_observer.cc
+++ b/chrome/browser/chromeos/extensions/extension_system_event_observer.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/chromeos/extensions/extension_system_event_observer.h"
 
 #include "chrome/browser/extensions/api/system_private/system_private_api.h"
+#include "chromeos/audio/cras_audio_handler.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 
 namespace chromeos {
@@ -12,11 +13,14 @@ namespace chromeos {
 ExtensionSystemEventObserver::ExtensionSystemEventObserver() {
   DBusThreadManager::Get()->GetPowerManagerClient()->AddObserver(this);
   DBusThreadManager::Get()->GetSessionManagerClient()->AddObserver(this);
+  CrasAudioHandler::Get()->AddAudioObserver(this);
 }
 
 ExtensionSystemEventObserver::~ExtensionSystemEventObserver() {
   DBusThreadManager::Get()->GetPowerManagerClient()->RemoveObserver(this);
   DBusThreadManager::Get()->GetSessionManagerClient()->RemoveObserver(this);
+  if (CrasAudioHandler::IsInitialized())
+    CrasAudioHandler::Get()->RemoveAudioObserver(this);
 }
 
 void ExtensionSystemEventObserver::BrightnessChanged(int level,
@@ -33,4 +37,19 @@ void ExtensionSystemEventObserver::ScreenIsUnlocked() {
   extensions::DispatchScreenUnlockedEvent();
 }
 
+void ExtensionSystemEventObserver::OnOutputNodeVolumeChanged(uint64_t node_id,
+                                                             int volume) {
+  CrasAudioHandler* audio_handler = CrasAudioHandler::Get();
+  extensions::DispatchVolumeChangedEvent(
+      audio_handler->GetOutputVolumePercent(), audio_handler->IsOutputMuted());
+}
+
+void ExtensionSystemEventObserver::OnOutputMuteChanged(
+    bool /* mute_on */,
+    bool /* system_adjust */) {
+  CrasAudioHandler* audio_handler = CrasAudioHandler::Get();

[sky, 2016/10/20 15:41:07]

This is the same as OnOutputMuteChanged. Move to common function, perhaps
DispatchVolumeChangedEvent()?

[msw, 2016/10/20 16:15:32]

Done.

+  extensions::DispatchVolumeChangedEvent(
+      audio_handler->GetOutputVolumePercent(), audio_handler->IsOutputMuted());
+}
+
 }  // namespace chromeos