Reland: CC: Adjust tiling creation triggers during pinch-zoom.

cc/layers/picture_layer_impl.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_LAYERS_PICTURE_LAYER_IMPL_H_
 #define CC_LAYERS_PICTURE_LAYER_IMPL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 64 matching lines @@
 
  protected:
   PictureLayerImpl(LayerTreeImpl* tree_impl, int id);
   PictureLayerTiling* AddTiling(float contents_scale);
   void RemoveTiling(float contents_scale);
   void RemoveAllTilings();
   void SyncFromActiveLayer(const PictureLayerImpl* other);
   void ManageTilings(bool animating_transform_to_screen);
   virtual bool ShouldAdjustRasterScale(
       bool animating_transform_to_screen) const;
-  virtual void CalculateRasterContentsScale(
-      bool animating_transform_to_screen,
-      float* raster_contents_scale,
-      float* low_res_raster_contents_scale) const;
+  virtual void RecalculateRasterScales(
+      bool animating_transform_to_screen);
   void CleanUpTilingsOnActiveLayer(
       std::vector<PictureLayerTiling*> used_tilings);
   float MinimumContentsScale() const;
+  float SnappedContentsScale(float new_contents_scale);
   void UpdateLCDTextStatus(bool new_status);
   void ResetRasterScale();
   void MarkVisibleResourcesAsRequired() const;
   void DoPostCommitInitializationIfNeeded() {
     if (needs_post_commit_initialization_)
       DoPostCommitInitialization();
   }
   void DoPostCommitInitialization();
 
   bool CanHaveTilings() const;
@@ skipping 33 matching lines @@
   // after a CalculateContentsScale/ManageTilings.
   bool should_update_tile_priorities_;
 
   friend class PictureLayer;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_LAYER_IMPL_H_