Use float for scroll offset.

third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ViewportScrollCallback_h
 #define ViewportScrollCallback_h
 
 #include "core/page/scrolling/ScrollStateCallback.h"
 #include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollTypes.h"
@@ skipping 38 matching lines @@
 
   DECLARE_VIRTUAL_TRACE();
 
  private:
   // ViewportScrollCallback does not assume ownership of TopControls or of
   // OverscrollController.
   ViewportScrollCallback(TopControls*,
                          OverscrollController*,
                          RootFrameViewport&);
 
-  bool shouldScrollTopControls(const FloatSize&, ScrollGranularity) const;
+  bool shouldScrollTopControls(const ScrollOffset&, ScrollGranularity) const;
   bool scrollTopControls(ScrollState&);
 
   ScrollResult performNativeScroll(ScrollState&);
 
   WeakMember<TopControls> m_topControls;
   WeakMember<OverscrollController> m_overscrollController;
   WeakMember<RootFrameViewport> m_rootFrameViewport;
 };
 
 }  // namespace blink
 
 #endif  // ViewportScrollCallback_h