Made Blink aware of top controls offset (Blink-side)

public/web/WebWidget.h

Index: public/web/WebWidget.h
diff --git a/public/web/WebWidget.h b/public/web/WebWidget.h
index 7d41f7bba823033a714a6c3825ba533e29968608..b8cd27940a6b0bc31cf3176454b10d2ad273501e 100644
--- a/public/web/WebWidget.h
+++ b/public/web/WebWidget.h
@@ -143,11 +143,18 @@ public:
     // Check whether the given point hits any registered touch event handlers.
     virtual bool hasTouchEventHandlersAt(const WebPoint&) { return true; }
 
-    // Applies a scroll delta to the root layer, which is bundled with a page
-    // scale factor that may apply a CSS transform on the whole document (used
-    // for mobile-device pinch zooming). This is triggered by events sent to the
-    // compositor thread.
-    virtual void applyScrollAndScale(const WebSize& scrollDelta, float scaleFactor) { }
+    // FIXME(bokan): Remove once Chromium-side patch lands
+    virtual void applyScrollAndScale(const WebSize& scrollDelta, float scaleFactor)
+    {
+        applyViewportDeltas(scrollDelta, scaleFactor, 0);
+    }
+
+    // Applies viewport related properties during a commit from the compositor
+    // thread.
+    virtual void applyViewportDeltas(
+        const WebSize& scrollDelta,
+        float scaleFactor,
+        float topControlsDelta) { }
 
     // Called to inform the WebWidget that mouse capture was lost.
     virtual void mouseCaptureLost() { }