Make scroll offset type of float in cc

cc/blink/web_layer_impl.h

Index: cc/blink/web_layer_impl.h
diff --git a/cc/blink/web_layer_impl.h b/cc/blink/web_layer_impl.h
index 3a8130e30b4b068fa45108b7cbf1bdc3aa123bf2..2b79500e34e1f683a6f377118719894bb50ca28e 100644
--- a/cc/blink/web_layer_impl.h
+++ b/cc/blink/web_layer_impl.h
@@ -6,6 +6,7 @@
 #define CC_BLINK_WEB_LAYER_IMPL_H_
 
 #include <string>
+#include <utility>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ -102,6 +103,10 @@ class WebLayerImpl : public blink::WebLayer, public cc::LayerClient {
   virtual void pauseAnimation(int animation_id, double time_offset);
   virtual bool hasActiveAnimation();
   virtual void setForceRenderSurface(bool force);
+  // TODO(miletus): Remove the WebPoint version once blink side starts to
+  // use the std:pair<double, double> version.
+  virtual void setScrollPositionFloat(const std::pair<double, double>&);
+  virtual std::pair<double, double> scrollPositionFloat() const;
   virtual void setScrollPosition(blink::WebPoint position);
   virtual blink::WebPoint scrollPosition() const;
   virtual void setScrollClipLayer(blink::WebLayer* clip_layer);