cc: Do not ignore layers without valid priorities during eviction.

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 <set>
 #include <string>
 #include <vector>
@@ skipping 108 matching lines @@
   // PictureLayerTilingClient overrides.
   scoped_refptr<Tile> CreateTile(PictureLayerTiling* tiling,
                                  const gfx::Rect& content_rect) override;
   RasterSource* GetRasterSource() override;
   gfx::Size CalculateTileSize(const gfx::Size& content_bounds) const override;
   const Region* GetPendingInvalidation() override;
   const PictureLayerTiling* GetPendingOrActiveTwinTiling(
       const PictureLayerTiling* tiling) const override;
   PictureLayerTiling* GetRecycledTwinTiling(
       const PictureLayerTiling* tiling) override;
+  TilePriority::PriorityBin GetMaxTilePriorityBin() const override;
   size_t GetMaxTilesForInterestArea() const override;
   float GetSkewportTargetTimeInSeconds() const override;
   int GetSkewportExtrapolationLimitInContentPixels() const override;
   WhichTree GetTree() const override;
   bool RequiresHighResToDraw() const override;
 
   // PushPropertiesTo active tree => pending tree.
   void SyncTiling(const PictureLayerTiling* tiling);
 
   // Mask-related functions.
@@ skipping 84 matching lines @@
   // frame that has a valid viewport for prioritizing tiles.
   gfx::Rect visible_rect_for_tile_priority_;
 
   friend class PictureLayer;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_LAYER_IMPL_H_