cc: Change preraster/predecode split to be half of max skewport extent.

cc/tiles/tile_manager.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_TILES_TILE_MANAGER_H_
 #define CC_TILES_TILE_MANAGER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 80 matching lines @@
 
 // This class manages tiles, deciding which should get rasterized and which
 // should no longer have any memory assigned to them. Tile objects are "owned"
 // by layers; they automatically register with the manager when they are
 // created, and unregister from the manager when they are deleted.
 class CC_EXPORT TileManager {
  public:
   TileManager(TileManagerClient* client,
               base::SequencedTaskRunner* task_runner,
               size_t scheduled_raster_task_limit,
-              bool use_partial_raster,
-              int max_preraster_distance_in_screen_pixels);
+              bool use_partial_raster);
   virtual ~TileManager();
 
   // Assigns tile memory and schedules work to prepare tiles for drawing.
   // - Runs client_->NotifyReadyToActivate() when all tiles required for
   // activation are prepared, or failed to prepare due to OOM.
   // - Runs client_->NotifyReadyToDraw() when all tiles required draw are
   // prepared, or failed to prepare due to OOM.
   bool PrepareTiles(const GlobalStateThatImpactsTilePriority& state);
 
   // Synchronously finish any in progress work, cancel the rest, and clean up as
@@ skipping 218 matching lines @@
   Signals signals_;
 
   UniqueNotifier signals_check_notifier_;
 
   bool has_scheduled_tile_tasks_;
 
   uint64_t prepare_tiles_count_;
   uint64_t next_tile_id_;
 
   std::unordered_map<Tile::Id, std::vector<DrawImage>> scheduled_draw_images_;
-  const int max_preraster_distance_in_screen_pixels_;
   std::vector<std::pair<DrawImage, scoped_refptr<TileTask>>> locked_images_;
 
   base::WeakPtrFactory<TileManager> task_set_finished_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TileManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_TILE_MANAGER_H_