cc: Fix size_t to int truncations in tiles/ and trees/

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 <deque>
 #include <queue>
 #include <set>
@@ skipping 195 matching lines @@
 
   void AssignGpuMemoryToTiles(
       RasterTilePriorityQueue* raster_priority_queue,
       size_t scheduled_raser_task_limit,
       PrioritizedTileVector* tiles_that_need_to_be_rasterized);
 
  private:
   class MemoryUsage {
    public:
     MemoryUsage();
-    MemoryUsage(int64 memory_bytes, int resource_count);
+    MemoryUsage(size_t memory_bytes, size_t resource_count);

[danakj, 2015/06/09 20:16:45]

Why are these size_t then if the stuff inside won't be?

[vmpstr, 2015/06/09 20:27:33]

The public interface to MemoryUsage uses size_t, since they represent a memory
usage. You can't construct something from negative values... Internally it needs
signness to make sure Exceeds works properly with memory usages that were
computed using subtraction. I mean it could use size_t with extra size_ts to
indicate how much more was subtracted than was available, but that's kind of
very convenient to represent as a signed number...

I could change the ctor to take int64 and int, but then on construction there
would be a cast? I'm not sure if that's better.

 
     static MemoryUsage FromConfig(const gfx::Size& size, ResourceFormat format);
     static MemoryUsage FromTile(const Tile* tile);
 
     MemoryUsage& operator+=(const MemoryUsage& other);
     MemoryUsage& operator-=(const MemoryUsage& other);
     MemoryUsage operator-(const MemoryUsage& other);
 
     bool Exceeds(const MemoryUsage& limit) const;
-    int64 memory_bytes() const { return memory_bytes_; }
+    size_t memory_bytes() const {

[danakj, 2015/06/09 20:29:42]

Can you make this return an int(64?) instead then?

[vmpstr, 2015/06/09 21:00:55]

Done.

+      // This is used for HUD layers / logging, so we can just static_cast here.
+      DCHECK_GE(memory_bytes_, 0);
+      return static_cast<size_t>(memory_bytes_);
+    }
 
    private:
     int64 memory_bytes_;
     int resource_count_;
   };
 
   void OnImageDecodeTaskCompleted(int layer_id,
                                   SkPixelRef* pixel_ref,
                                   bool was_canceled);
   void OnRasterTaskCompleted(Tile::Id tile,
@@ skipping 69 matching lines @@
 
   bool did_notify_ready_to_activate_;
   bool did_notify_ready_to_draw_;
 
   DISALLOW_COPY_AND_ASSIGN(TileManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_TILE_MANAGER_H_