cc: Plumb more details about pixel refs to tile manager.

skia/ext/pixel_ref_utils.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 SKIA_EXT_PIXEL_REF_UTILS_H_
 #define SKIA_EXT_PIXEL_REF_UTILS_H_
 
 #include <vector>
 
 #include "SkPicture.h"
 #include "SkRect.h"
 
 namespace skia {
 
 class SK_API PixelRefUtils {
  public:
 
   struct PositionPixelRef {
     SkPixelRef* pixel_ref;
     SkRect pixel_ref_rect;
     SkMatrix matrix;
     SkFilterQuality filter_quality;
   };
 
   static void GatherDiscardablePixelRefs(
       SkPicture* picture,
       std::vector<PositionPixelRef>* pixel_refs);
 };
 
-typedef std::vector<PixelRefUtils::PositionPixelRef> DiscardablePixelRefList;
+using PositionPixelRef = PixelRefUtils::PositionPixelRef;
+using DiscardablePixelRefList = std::vector<PositionPixelRef>;
 
 }  // namespace skia
 
 #endif