Constify SkPicture in DrawingDisplayItem (cc side)

cc/resources/drawing_display_item.h

Index: cc/resources/drawing_display_item.h
diff --git a/cc/resources/drawing_display_item.h b/cc/resources/drawing_display_item.h
index 1f63ed34e2e9c05bb25ab5307c54c47089bebafa..8359d61fb1c88e2574d1e9b2fec1336baf322239 100644
--- a/cc/resources/drawing_display_item.h
+++ b/cc/resources/drawing_display_item.h
@@ -9,7 +9,6 @@
 #include "cc/base/cc_export.h"
 #include "cc/resources/display_item.h"
 #include "skia/ext/refptr.h"
-#include "ui/gfx/geometry/point_f.h"
 
 class SkCanvas;
 class SkDrawPictureCallback;
@@ -21,9 +20,9 @@ class CC_EXPORT DrawingDisplayItem : public DisplayItem {
  public:
   ~DrawingDisplayItem() override;
 
-  static scoped_ptr<DrawingDisplayItem> Create(skia::RefPtr<SkPicture> picture,
-                                               gfx::PointF location) {
-    return make_scoped_ptr(new DrawingDisplayItem(picture, location));
+  static scoped_ptr<DrawingDisplayItem> Create(
+      skia::RefPtr<const SkPicture> picture) {
+    return make_scoped_ptr(new DrawingDisplayItem(picture));
   }
 
   void Raster(SkCanvas* canvas, SkDrawPictureCallback* callback) const override;
@@ -35,11 +34,10 @@ class CC_EXPORT DrawingDisplayItem : public DisplayItem {
   void AsValueInto(base::trace_event::TracedValue* array) const override;
 
  protected:
-  DrawingDisplayItem(skia::RefPtr<SkPicture> picture, gfx::PointF location);
+  explicit DrawingDisplayItem(skia::RefPtr<const SkPicture> picture);
 
  private:
-  skia::RefPtr<SkPicture> picture_;
-  gfx::PointF location_;
+  skia::RefPtr<const SkPicture> picture_;
 };
 
 }  // namespace cc