Revert of Remove default args to several PageWidgetDelegate members.

Source/web/PageWidgetDelegate.h

Index: Source/web/PageWidgetDelegate.h
diff --git a/Source/web/PageWidgetDelegate.h b/Source/web/PageWidgetDelegate.h
index f2defaf7345b5a126d6baf2016c3300c797b821a..32200b8cb55e32adf2d36dd86b5ffbf41b8da61d 100644
--- a/Source/web/PageWidgetDelegate.h
+++ b/Source/web/PageWidgetDelegate.h
@@ -72,10 +72,10 @@
     // rootFrame arguments indicate a root localFrame from which to start performing the
     // specified operation. If rootFrame is 0, these methods will attempt to use the
     // Page's mainFrame(), if it is a LocalFrame.
-    static void animate(Page*, double monotonicFrameBeginTime, LocalFrame* root);
-    static void layout(Page*, LocalFrame* root);
-    static void paint(Page*, PageOverlayList*, WebCanvas*, const WebRect&, CanvasBackground, LocalFrame* root);
-    static bool handleInputEvent(Page*, PageWidgetEventHandler&, const WebInputEvent&, LocalFrame* root);
+    static void animate(Page*, double monotonicFrameBeginTime, LocalFrame* rootFrame = 0);
+    static void layout(Page*, LocalFrame* rootFrame = 0);
+    static void paint(Page*, PageOverlayList*, WebCanvas*, const WebRect&, CanvasBackground, LocalFrame* rootFrame = 0);
+    static bool handleInputEvent(Page*, PageWidgetEventHandler&, const WebInputEvent&, LocalFrame* rootFrame = 0);
 
 private:
     PageWidgetDelegate() { }