Move WebUIMessageHandler to its own file in the public directory and put it in the content namesp...

content/browser/webui/generic_handler.h

Index: content/browser/webui/generic_handler.h
===================================================================
--- content/browser/webui/generic_handler.h	(revision 116051)
+++ content/browser/webui/generic_handler.h	(working copy)
@@ -6,14 +6,15 @@
 #define CONTENT_BROWSER_WEBUI_GENERIC_HANDLER_H_
 #pragma once
 
-#include "content/browser/webui/web_ui.h"
+#include "base/compiler_specific.h"
+#include "content/public/browser/web_ui_message_handler.h"
 
 namespace base {
 class ListValue;
 }
 
 // A place to add handlers for messages shared across all WebUI pages.
-class GenericHandler : public WebUIMessageHandler {
+class GenericHandler : public content::WebUIMessageHandler {
  public:
   GenericHandler();
   virtual ~GenericHandler();