Allow browser compositor to create an offscreen context3D.

content/common/webkitplatformsupport_impl.h

Index: content/common/webkitplatformsupport_impl.h
diff --git a/content/common/webkitplatformsupport_impl.h b/content/common/webkitplatformsupport_impl.h
index 1904042cf26b9a8933b76dbbc1c904778db1862c..b0d6cbcdb8cf3e4b9c9fe558d048d46628b38b05 100644
--- a/content/common/webkitplatformsupport_impl.h
+++ b/content/common/webkitplatformsupport_impl.h
@@ -30,6 +30,8 @@ class CONTENT_EXPORT WebKitPlatformSupportImpl
   virtual webkit_glue::WebSocketStreamHandleBridge* CreateWebSocketBridge(
       WebKit::WebSocketStreamHandle* handle,
       webkit_glue::WebSocketStreamHandleDelegate* delegate) OVERRIDE;
+  virtual WebKit::WebGraphicsContext3D* createOffscreenGraphicsContext3D(
+      const WebKit::WebGraphicsContext3D::Attributes& attributes);
 };
 
 }  // namespace content