Add argument to pass elastic overscroll delta to Blink (Blink side)

public/web/WebWidget.h

Index: public/web/WebWidget.h
diff --git a/public/web/WebWidget.h b/public/web/WebWidget.h
index f2d2d2229f72810965fb9727b5e1c8281058b1e5..94e01c4e485e338bd5c98d8786354d7866a4eb73 100644
--- a/public/web/WebWidget.h
+++ b/public/web/WebWidget.h
@@ -33,6 +33,7 @@
 
 #include "../platform/WebCanvas.h"
 #include "../platform/WebCommon.h"
+#include "../platform/WebFloatSize.h"
 #include "../platform/WebPoint.h"
 #include "../platform/WebRect.h"
 #include "../platform/WebSize.h"
@@ -149,6 +150,13 @@ public:
     virtual void applyViewportDeltas(
         const WebSize& pinchViewportDelta,
         const WebSize& mainFrameDelta,
+        const WebFloatSize& elasticOverscrollDelta,
+        float scaleFactor,
+        float topControlsDelta) { }
+    // TODO(ccameron): Delete this when all callers are removed.
+    virtual void applyViewportDeltas(
+        const WebSize& pinchViewportDelta,
+        const WebSize& mainFrameDelta,
         float scaleFactor,
         float topControlsDelta) { }