Handle volume keys within Chrome

chrome/browser/chromeos/system_key_event_listener.h

Index: chrome/browser/chromeos/system_key_event_listener.h
diff --git a/chrome/browser/chromeos/system_key_event_listener.h b/chrome/browser/chromeos/system_key_event_listener.h
index b731b94064b7def40567e175fa26875d09cb9b92..fac16657df3e32577d132f3a0b519858c3543acd 100644
--- a/chrome/browser/chromeos/system_key_event_listener.h
+++ b/chrome/browser/chromeos/system_key_event_listener.h
@@ -6,25 +6,22 @@
 #define CHROME_BROWSER_CHROMEOS_SYSTEM_KEY_EVENT_LISTENER_H_
 #pragma once
 
+#include <gdk/gdk.h>
+
 #include "base/singleton.h"
-#include "chrome/browser/chromeos/wm_message_listener.h"
 
 namespace chromeos {
 
 class AudioHandler;
 
-// SystemKeyEventListener listens for volume related key presses from the
-// window manager, then tells the AudioHandler to adjust volume accordingly.
-// Start by just calling instance() to get it going.
+// SystemKeyEventListener listens for volume related key presses from GDK, then
+// tells the AudioHandler to adjust volume accordingly.  Start by just calling
+// instance() to get it going.
 
-class SystemKeyEventListener : public WmMessageListener::Observer {
+class SystemKeyEventListener {
  public:
   static SystemKeyEventListener* instance();
 
-  // WmMessageListener::Observer:
-  virtual void ProcessWmMessage(const WmIpc::Message& message,
-                                GdkWindow* window);
-
  private:
   // Defines the delete on exit Singleton traits we like.  Best to have this
   // and const/dest private as recommended for Singletons.
@@ -33,6 +30,28 @@ class SystemKeyEventListener : public WmMessageListener::Observer {
   SystemKeyEventListener();
   virtual ~SystemKeyEventListener();
 
+  // This event filter intercepts events before they reach GDK, allowing us to
+  // check for system level keyboard events regardless of which window has
+  // focus.
+  static GdkFilterReturn GdkEventFilter(GdkXEvent* gxevent,
+                                        GdkEvent* gevent,
+                                        gpointer data);
+
+  // Tell X we are interested in the specified key/mask combination.
+  // Capslock and Numlock are always ignored.
+  void GrabKey(int32 key, uint32 mask);
+
+  void OnVolumeMute();
+  void OnVolumeDown();
+  void OnVolumeUp();
+
+  int32 key_volume_mute_;
+  int32 key_volume_down_;
+  int32 key_volume_up_;
+  int32 key_f8_;
+  int32 key_f9_;
+  int32 key_f10_;
+
   // AudioHandler is a Singleton class we are just caching a pointer to here,
   // and we do not own the pointer.
   AudioHandler* const audio_handler_;