Plumb an event through to content/ that is sent just before 'onload'.

Source/WebKit/chromium/public/WebFrameClient.h

Index: Source/WebKit/chromium/public/WebFrameClient.h
diff --git a/Source/WebKit/chromium/public/WebFrameClient.h b/Source/WebKit/chromium/public/WebFrameClient.h
index f4781564bb9cf0a86788ce35a5cd1f52dd12b12a..58b20a218c4afc562eb9261df02a86f949393dd1 100644
--- a/Source/WebKit/chromium/public/WebFrameClient.h
+++ b/Source/WebKit/chromium/public/WebFrameClient.h
@@ -224,6 +224,9 @@ public:
     // The frame's document finished loading.
     virtual void didFinishDocumentLoad(WebFrame*) { }
 
+    // The 'load' event is about to be dispatched.
+    virtual void willHandleOnloadEvents(WebFrame*) { }
+
     // The 'load' event was dispatched.
     virtual void didHandleOnloadEvents(WebFrame*) { }