cc: Fix tiling raster tile iterator to handle initializing tiles.

cc/resources/picture_layer_tiling.cc

 // 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.
 
 #include "cc/resources/picture_layer_tiling.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 
@@ skipping 841 matching lines @@
     }
 
     while (spiral_iterator_) {
       current_tile_ = tiling_->TileAt(spiral_iterator_.index_x(),
                                       spiral_iterator_.index_y());
       if (current_tile_ && TileNeedsRaster(current_tile_))
         break;
       ++spiral_iterator_;
     }
 
-    if (!spiral_iterator_ && type_ == TilePriority::EVENTUALLY)
+    if (!spiral_iterator_ && type_ == TilePriority::EVENTUALLY) {
+      current_tile_ = NULL;
       break;
+    }
   } while (!spiral_iterator_);
 }
 
 PictureLayerTiling::TilingRasterTileIterator&
 PictureLayerTiling::TilingRasterTileIterator::
 operator++() {
   current_tile_ = NULL;
   while (!current_tile_ || !TileNeedsRaster(current_tile_)) {
     std::pair<int, int> next_index;
     switch (type_) {
@@ skipping 20 matching lines @@
               visible_rect_in_content_space_);
           if (!spiral_iterator_) {
             AdvancePhase();
             return *this;
           }
         }
         next_index = spiral_iterator_.index();
         break;
       case TilePriority::EVENTUALLY:
         ++spiral_iterator_;
-        if (!spiral_iterator_)
+        if (!spiral_iterator_) {
+          current_tile_ = NULL;
           return *this;
+        }
         next_index = spiral_iterator_.index();
         break;
     }
     current_tile_ = tiling_->TileAt(next_index.first, next_index.second);
   }
   return *this;
 }
 
 PictureLayerTiling::TilingEvictionTileIterator::TilingEvictionTileIterator()
     : is_valid_(false), tiling_(NULL) {}
@@ skipping 39 matching lines @@
   tiling_->UpdateEvictionCacheIfNeeded(tree_priority_);
   tile_iterator_ = tiling_->eviction_tiles_cache_.begin();
   is_valid_ = true;
   if (tile_iterator_ != tiling_->eviction_tiles_cache_.end() &&
       !(*tile_iterator_)->HasResources()) {
     ++(*this);
   }
 }
 
 }  // namespace cc