Update from https://crrev.com/304715

cc/resources/picture_layer_tiling_set.h

 // Copyright 2012 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 CC_RESOURCES_PICTURE_LAYER_TILING_SET_H_
 #define CC_RESOURCES_PICTURE_LAYER_TILING_SET_H_
 
+#include <set>
+
 #include "cc/base/region.h"
 #include "cc/base/scoped_ptr_vector.h"
 #include "cc/resources/picture_layer_tiling.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace base {
 namespace debug {
 class TracedValue;
 }
 }
@@ skipping 39 matching lines @@
 
   PictureLayerTiling* AddTiling(float contents_scale,
                                 const gfx::Size& layer_bounds);
   size_t num_tilings() const { return tilings_.size(); }
   int NumHighResTilings() const;
   PictureLayerTiling* tiling_at(size_t idx) { return tilings_[idx]; }
   const PictureLayerTiling* tiling_at(size_t idx) const {
     return tilings_[idx];
   }
 
-  PictureLayerTiling* TilingAtScale(float scale) const;
+  PictureLayerTiling* FindTilingWithScale(float scale) const;
+  PictureLayerTiling* FindTilingWithResolution(TileResolution resolution) const;
+
+  void MarkAllTilingsNonIdeal();
+
+  // If a tiling exists whose scale is within |snap_to_existing_tiling_ratio|
+  // ratio of |start_scale|, then return that tiling's scale. Otherwise, return
+  // |start_scale|. If multiple tilings match the criteria, return the one with
+  // the least ratio to |start_scale|.
+  float GetSnappedContentsScale(float start_scale,
+                                float snap_to_existing_tiling_ratio) const;
+
+  // Returns the maximum contents scale of all tilings, or 0 if no tilings
+  // exist.
+  float GetMaximumContentsScale() const;
 
   // Remove all tilings.
   void RemoveAllTilings();
 
   // Remove one tiling.
   void Remove(PictureLayerTiling* tiling);
+  void RemoveTilingWithScale(float scale);
 
   // Remove all tiles; keep all tilings.
   void RemoveAllTiles();
 
   // Update the rects and priorities for tiles based on the given information.
   bool UpdateTilePriorities(const gfx::Rect& required_rect_in_layer_space,
                             float ideal_contents_scale,
                             double current_frame_time_in_seconds,
                             const Occlusion& occlusion_in_layer_space,
                             bool can_require_tiles_for_activation);
 
+  void GetAllTilesForTracing(std::set<const Tile*>* tiles) const;
+
   // For a given rect, iterates through tiles that can fill it.  If no
   // set of tiles with resources can fill the rect, then it will iterate
   // through null tiles with valid geometry_rect() until the rect is full.
   // If all tiles have resources, the union of all geometry_rects will
   // exactly fill rect with no overlap.
   class CC_EXPORT CoverageIterator {
    public:
     CoverageIterator(const PictureLayerTilingSet* set,
       float contents_scale,
       const gfx::Rect& content_rect,
@@ skipping 43 matching lines @@
   PictureLayerTilingClient* client_;
   ScopedPtrVector<PictureLayerTiling> tilings_;
 
   friend class Iterator;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerTilingSet);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_LAYER_TILING_SET_H_