cc: Eliminate refcount churn in prioritized tile's raster source.

cc/tiles/prioritized_tile.cc

 // Copyright 2015 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.
 
 #include "cc/tiles/prioritized_tile.h"
 
 #include "cc/debug/traced_value.h"
 #include "cc/tiles/picture_layer_tiling.h"
 
 namespace cc {
 
-PrioritizedTile::PrioritizedTile() : tile_(nullptr), is_occluded_(false) {}
+PrioritizedTile::PrioritizedTile() = default;
 
 PrioritizedTile::PrioritizedTile(Tile* tile,
-                                 scoped_refptr<RasterSource> raster_source,
+                                 const PictureLayerTiling* source_tiling,
                                  const TilePriority priority,
                                  bool is_occluded)
     : tile_(tile),
-      raster_source_(std::move(raster_source)),
+      source_tiling_(source_tiling),
       priority_(priority),
       is_occluded_(is_occluded) {}
 
-PrioritizedTile::PrioritizedTile(const PrioritizedTile& other) = default;
-PrioritizedTile::PrioritizedTile(PrioritizedTile&& other) = default;
 PrioritizedTile::~PrioritizedTile() = default;
 
-PrioritizedTile& PrioritizedTile::operator=(const PrioritizedTile& other) =
-    default;
-PrioritizedTile& PrioritizedTile::operator=(PrioritizedTile&& other) = default;
-
 void PrioritizedTile::AsValueInto(base::trace_event::TracedValue* value) const {
   tile_->AsValueInto(value);
 
   TracedValue::SetIDRef(raster_source().get(), value, "picture_pile");
 
   value->BeginDictionary("combined_priority");
   priority().AsValueInto(value);
   value->SetBoolean("is_occluded", is_occluded_);
   value->EndDictionary();
 
   value->SetString("resolution", TileResolutionToString(priority().resolution));
 }
 
 }  // namespace cc