Forward declare v8::Extension in chrome/renderer/extensions/*.

chrome/renderer/extensions/extension_process_bindings.h

Index: chrome/renderer/extensions/extension_process_bindings.h
diff --git a/chrome/renderer/extensions/extension_process_bindings.h b/chrome/renderer/extensions/extension_process_bindings.h
index d72ecc1d161b829378cbeb449109b03365313e05..c636cf0968d26ad35c57e4202821817a32f3bb57 100644
--- a/chrome/renderer/extensions/extension_process_bindings.h
+++ b/chrome/renderer/extensions/extension_process_bindings.h
@@ -12,8 +12,6 @@
 #include <string>
 #include <vector>
 
-#include "v8/include/v8.h"
-
 class ExtensionRendererContext;
 class GURL;
 class URLPattern;
@@ -22,6 +20,10 @@ namespace WebKit {
 class WebView;
 }
 
+namespace v8 {
+class Extension;
+}
+
 class ExtensionProcessBindings {
  public:
   static v8::Extension* Get(