cc: Fix layer raster tile iterator not to skip a tile erroneously.

cc/layers/picture_layer_impl.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/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 
@@ skipping 1550 matching lines @@
 
   stages_[2].iterator_type = HIGH_RES;
   stages_[2].tile_type = TilePriority::SOON;
 
   stages_[3].iterator_type = HIGH_RES;
   stages_[3].tile_type = TilePriority::EVENTUALLY;
 
   IteratorType index = stages_[current_stage_].iterator_type;
   TilePriority::PriorityBin tile_type = stages_[current_stage_].tile_type;
   if (!iterators_[index] || iterators_[index].get_type() != tile_type)
-    ++(*this);
+    AdvanceToNextStage();
 }
 
 PictureLayerImpl::LayerRasterTileIterator::~LayerRasterTileIterator() {}
 
 PictureLayerImpl::LayerRasterTileIterator::operator bool() const {
   return current_stage_ < arraysize(stages_);
 }
 
 PictureLayerImpl::LayerRasterTileIterator&
 PictureLayerImpl::LayerRasterTileIterator::
 operator++() {
   IteratorType index = stages_[current_stage_].iterator_type;
   TilePriority::PriorityBin tile_type = stages_[current_stage_].tile_type;
 
   // First advance the iterator.
-  if (iterators_[index])
-    ++iterators_[index];
+  DCHECK(iterators_[index]);
+  DCHECK(iterators_[index].get_type() == tile_type);
+  ++iterators_[index];
 
-  if (iterators_[index] && iterators_[index].get_type() == tile_type)
-    return *this;
+  if (!iterators_[index] || iterators_[index].get_type() != tile_type)
+    AdvanceToNextStage();
 
-  // Next, advance the stage.
-  ++current_stage_;
-  while (current_stage_ < arraysize(stages_)) {
-    index = stages_[current_stage_].iterator_type;
-    tile_type = stages_[current_stage_].tile_type;
-
-    if (iterators_[index] && iterators_[index].get_type() == tile_type)
-      break;
-    ++current_stage_;
-  }
   return *this;
 }
 
 Tile* PictureLayerImpl::LayerRasterTileIterator::operator*() {
   DCHECK(*this);
 
   IteratorType index = stages_[current_stage_].iterator_type;
   DCHECK(iterators_[index]);
   DCHECK(iterators_[index].get_type() == stages_[current_stage_].tile_type);
 
   return *iterators_[index];
 }
 
 const Tile* PictureLayerImpl::LayerRasterTileIterator::operator*() const {
   DCHECK(*this);
 
   IteratorType index = stages_[current_stage_].iterator_type;
   DCHECK(iterators_[index]);
   DCHECK(iterators_[index].get_type() == stages_[current_stage_].tile_type);
 
   return *iterators_[index];
 }
 
+void PictureLayerImpl::LayerRasterTileIterator::AdvanceToNextStage() {
+  DCHECK_LT(current_stage_, arraysize(stages_));
+  ++current_stage_;
+  while (current_stage_ < arraysize(stages_)) {
+    IteratorType index = stages_[current_stage_].iterator_type;
+    TilePriority::PriorityBin tile_type = stages_[current_stage_].tile_type;
+
+    if (iterators_[index] && iterators_[index].get_type() == tile_type)
+      break;
+    ++current_stage_;
+  }
+}
+
 PictureLayerImpl::LayerEvictionTileIterator::LayerEvictionTileIterator()
     : layer_(NULL),
       tree_priority_(SAME_PRIORITY_FOR_BOTH_TREES),
       current_category_(PictureLayerTiling::EVENTUALLY),
       current_tiling_range_type_(PictureLayerTilingSet::HIGHER_THAN_HIGH_RES),
       current_tiling_(0u) {
 }
 
 PictureLayerImpl::LayerEvictionTileIterator::LayerEvictionTileIterator(
     PictureLayerImpl* layer,
@@ skipping 134 matching lines @@
       PictureLayerTilingSet::TilingRange tiling_range = CurrentTilingRange();
       size_t current_tiling_range_offset = current_tiling_ - tiling_range.start;
       return tiling_range.end - 1 - current_tiling_range_offset;
     }
   }
   NOTREACHED();
   return 0;
 }
 
 }  // namespace cc