cc: Move raster_source from Tile to PrioritizedTile

cc/resources/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/resources/prioritized_tile.h"
 
 #include "cc/resources/picture_layer_tiling.h"
 
 namespace cc {
 
-PrioritizedTile::PrioritizedTile() : tile_(nullptr), is_occluded_(false) {
+PrioritizedTile::PrioritizedTile()
+    : tile_(nullptr), raster_source_(nullptr), is_occluded_(false) {
 }
 
 PrioritizedTile::PrioritizedTile(Tile* tile,
+                                 RasterSource* raster_source,
                                  const TilePriority priority,
                                  bool is_occluded)
-    : tile_(tile), priority_(priority), is_occluded_(is_occluded) {
+    : tile_(tile),
+      raster_source_(raster_source),
+      priority_(priority),
+      is_occluded_(is_occluded) {
 }
 
 PrioritizedTile::~PrioritizedTile() {
 }
 
 }  // namespace cc