Use float for scroll offset.

cc/blink/web_layer_impl.h

 // Copyright 2014 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 CC_BLINK_WEB_LAYER_IMPL_H_
 #define CC_BLINK_WEB_LAYER_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 81 matching lines @@
   void setDoubleSided(bool double_sided) override;
   void setShouldFlattenTransform(bool flatten) override;
   void setRenderingContext(int context) override;
   void setUseParentBackfaceVisibility(bool visible) override;
   void setBackgroundColor(blink::WebColor color) override;
   blink::WebColor backgroundColor() const override;
   void setFilters(const cc::FilterOperations& filters) override;
   void setFiltersOrigin(const blink::WebFloatPoint& origin) override;
   void setBackgroundFilters(const cc::FilterOperations& filters) override;
   bool hasActiveAnimationForTesting() override;
-  void setScrollPositionDouble(blink::WebDoublePoint position) override;
-  blink::WebDoublePoint scrollPositionDouble() const override;
+  void setScrollOffset(blink::WebFloatSize position) override;
+  blink::WebFloatSize scrollOffset() const override;
   void setScrollClipLayer(blink::WebLayer* clip_layer) override;
   bool scrollable() const override;
   void setUserScrollable(bool horizontal, bool vertical) override;
   bool userScrollableHorizontal() const override;
   bool userScrollableVertical() const override;
   void addMainThreadScrollingReasons(
       uint32_t main_thread_scrolling_reasons) override;
   void clearMainThreadScrollingReasons(
       uint32_t main_thread_scrolling_reasons_to_clear) override;
   uint32_t mainThreadScrollingReasons() override;
@@ skipping 31 matching lines @@
 
   bool contents_opaque_is_fixed_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WebLayerImpl);
 };
 
 }  // namespace cc_blink
 
 #endif  // CC_BLINK_WEB_LAYER_IMPL_H_