cc: Remove separate x/y raster scales.

cc/playback/raster_source.h

Index: cc/playback/raster_source.h
diff --git a/cc/playback/raster_source.h b/cc/playback/raster_source.h
index ad7e5acdc442425f6f855e04cf27496bdca92c3f..471f7ba6ee479e616621729cf55bee52c1c6b1a4 100644
--- a/cc/playback/raster_source.h
+++ b/cc/playback/raster_source.h
@@ -51,7 +51,7 @@ class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
   void PlaybackToCanvas(SkCanvas* canvas,
                         const gfx::Rect& canvas_bitmap_rect,
                         const gfx::Rect& canvas_playback_rect,
-                        const gfx::SizeF& raster_scales,
+                        float contents_scale,
                         const PlaybackSettings& settings) const;
 
   // Raster this RasterSource into the given canvas. Canvas states such as
@@ -69,7 +69,7 @@ class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
   // Returns whether the given rect at given scale is of solid color in
   // this raster source, as well as the solid color value.
   bool PerformSolidColorAnalysis(const gfx::Rect& content_rect,
-                                 const gfx::SizeF& raster_scales,
+                                 float contents_scale,
                                  SkColor* color) const;
 
   // Returns true iff the whole raster source is of solid color.
@@ -94,7 +94,7 @@ class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
   // rect in layer space. The returned draw images' matrices are modified as if
   // they were being using during raster at scale |raster_scale|.
   void GetDiscardableImagesInRect(const gfx::Rect& layer_rect,
-                                  const gfx::SizeF& raster_scales,
+                                  float contents_scale,
                                   std::vector<DrawImage>* images) const;
 
   // Return true iff this raster source can raster the given rect in layer