cc: Avoid redraw for missing tile outside visible rect

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 154 matching lines @@
   float MinimumContentsScale() const;
   float SnappedContentsScale(float new_contents_scale);
   void ResetRasterScale();
   void MarkVisibleResourcesAsRequired() const;
   bool MarkVisibleTilesAsRequired(
       PictureLayerTiling* tiling,
       const PictureLayerTiling* optional_twin_tiling,
       float contents_scale,
       const gfx::Rect& rect,
       const Region& missing_region) const;
+  gfx::Rect GetViewportForTilePriorityInContentSpace() const;
 
   void DoPostCommitInitializationIfNeeded() {
     if (needs_post_commit_initialization_)
       DoPostCommitInitialization();
   }
   void DoPostCommitInitialization();
 
   bool CanHaveTilings() const;
   bool CanHaveTilingWithScale(float contents_scale) const;
   void SanityCheckTilingState() const;
@@ skipping 37 matching lines @@
   gfx::Rect viewport_rect_for_tile_priority_;
   gfx::Transform screen_space_transform_for_tile_priority_;
 
   friend class PictureLayer;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_LAYER_IMPL_H_