Pass accurate contentsScale to LayerImpl.

cc/layer_impl.h

Index: cc/layer_impl.h
diff --git a/cc/layer_impl.h b/cc/layer_impl.h
index 05f3b44f374c6259dd281adb592abeaf90ce17d3..c243e72fd9d4e2ed30d17156d07e98708dfb9111 100644
--- a/cc/layer_impl.h
+++ b/cc/layer_impl.h
@@ -170,8 +170,11 @@ public:
     void setBounds(const IntSize&);
     const IntSize& bounds() const { return m_bounds; }
 
-    const IntSize& contentBounds() const { return m_contentBounds; }
-    void setContentBounds(const IntSize&);
+    IntSize contentBounds() const;
+
+    float contentsScaleX() const { return m_contentsScaleX; }
+    float contentsScaleY() const { return m_contentsScaleY; }
+    void setContentsScale(float contentsScaleX, float contentsScaleY);
 
     const IntPoint& scrollPosition() const { return m_scrollPosition; }
     void setScrollPosition(const IntPoint&);
@@ -300,6 +303,8 @@ private:
     float m_anchorPointZ;
     IntSize m_bounds;
     IntSize m_contentBounds;
+    float m_contentsScaleX;
+    float m_contentsScaleY;
     IntPoint m_scrollPosition;
     bool m_scrollable;
     bool m_shouldScrollOnMainThread;