renderer/extensions: Forward declare a couple of v8 classes in EventBindings header.

chrome/renderer/extensions/event_bindings.h

Index: chrome/renderer/extensions/event_bindings.h
diff --git a/chrome/renderer/extensions/event_bindings.h b/chrome/renderer/extensions/event_bindings.h
index e4857e3c2aa883c72ea171af3d776448776fbaae..75deefb4c12fc60d7d4353138e26e717ec582684 100644
--- a/chrome/renderer/extensions/event_bindings.h
+++ b/chrome/renderer/extensions/event_bindings.h
@@ -8,8 +8,6 @@
 
 #include <string>
 
-#include "v8/include/v8.h"
-
 class ExtensionDispatcher;
 class GURL;
 class RenderThreadBase;
@@ -19,6 +17,12 @@ namespace base {
 class ListValue;
 }
 
+namespace v8 {
+class Context;
+class Extension;
+template <class T> class Handle;
+}
+
 namespace WebKit {
 class WebFrame;
 }