Adds the ability to observer messages from the window manager....

chrome/browser/chromeos/wm_message_listener.h

Index: chrome/browser/chromeos/wm_message_listener.h
===================================================================
--- chrome/browser/chromeos/wm_message_listener.h	(revision 40691)
+++ chrome/browser/chromeos/wm_message_listener.h	(working copy)
@@ -8,6 +8,7 @@
 #include <gtk/gtk.h>
 
 #include "base/message_loop.h"
+#include "base/observer_list.h"
 #include "base/singleton.h"
 #include "chrome/browser/chromeos/wm_ipc.h"
 
@@ -18,10 +19,27 @@
 
 // WmMessageListener listens for messages from the window manager that need to
 // be dealt with by Chrome.
+// To listen for window manager messages add an observer.
 class WmMessageListener : public MessageLoopForUI::Observer {
  public:
+  // Observer is notified any time a message is received from the window
+  // manager.
+  class Observer {
+   public:
+    virtual void ProcessWmMessage(const WmIpc::Message& message,
+                                  GdkWindow* window) = 0;
+  };
+
   static WmMessageListener* instance();
 
+  void AddObserver(Observer* observer) {
+    observers_.AddObserver(observer);
+  }
+
+  void RemoveObserver(Observer* observer) {
+    observers_.RemoveObserver(observer);
+  }
+
   // MessageLoopForUI::Observer overrides.
   virtual void WillProcessEvent(GdkEvent* event);
   virtual void DidProcessEvent(GdkEvent* event);
@@ -35,6 +53,8 @@
   // Invoked when a valid WmIpc::Message is received.
   void ProcessMessage(const WmIpc::Message& message, GdkWindow* window);
 
+  ObserverList<Observer> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(WmMessageListener);
 };