cc: Optimize OnePriorityRectIterator a little bit.

cc/tiles/tiling_set_raster_queue_all.cc

Index: cc/tiles/tiling_set_raster_queue_all.cc
diff --git a/cc/tiles/tiling_set_raster_queue_all.cc b/cc/tiles/tiling_set_raster_queue_all.cc
index ae91f271fc2057d858e4532dcf450b28f0aef74d..54e25623cb9f8a31d7ef95796684ed0b18e8410b 100644
--- a/cc/tiles/tiling_set_raster_queue_all.cc
+++ b/cc/tiles/tiling_set_raster_queue_all.cc
@@ -158,14 +158,18 @@ TilingSetRasterQueueAll::OnePriorityRectIterator::OnePriorityRectIterator(
 template <typename TilingIteratorType>
 void TilingSetRasterQueueAll::OnePriorityRectIterator::AdvanceToNextTile(
     TilingIteratorType* iterator) {
-  bool found_tile = false;
-  while (!found_tile) {
+  for (;;) {
     ++(*iterator);
     if (!(*iterator)) {
       current_tile_ = PrioritizedTile();
       break;
     }
-    found_tile = GetFirstTileAndCheckIfValid(iterator);
+    Tile* tile = tiling_->TileAt(iterator->index_x(), iterator->index_y());
+    if (IsTileValid(tile)) {
+      tiling_->UpdateRequiredStatesOnTile(tile);
+      current_tile_ = tiling_->MakePrioritizedTile(tile, priority_rect_type_);
+      break;
+    }
   }
 }
 
@@ -173,20 +177,26 @@ template <typename TilingIteratorType>
 bool TilingSetRasterQueueAll::OnePriorityRectIterator::
     GetFirstTileAndCheckIfValid(TilingIteratorType* iterator) {
   Tile* tile = tiling_->TileAt(iterator->index_x(), iterator->index_y());
-  if (!tile || !TileNeedsRaster(tile)) {
+  if (!IsTileValid(tile)) {
     current_tile_ = PrioritizedTile();
     return false;
   }
+  tiling_->UpdateRequiredStatesOnTile(tile);
+  current_tile_ = tiling_->MakePrioritizedTile(tile, priority_rect_type_);
+  return true;
+}
+
+bool TilingSetRasterQueueAll::OnePriorityRectIterator::IsTileValid(
+    const Tile* tile) const {
+  if (!tile || !TileNeedsRaster(tile))
+    return false;
   // After the pending visible rect has been processed, we must return false
   // for pending visible rect tiles as tiling iterators do not ignore those
   // tiles.
   if (priority_rect_type_ > PictureLayerTiling::PENDING_VISIBLE_RECT &&
       tiling_->pending_visible_rect().Intersects(tile->content_rect())) {
-    current_tile_ = PrioritizedTile();
     return false;
   }
-  tiling_->UpdateRequiredStatesOnTile(tile);
-  current_tile_ = tiling_->MakePrioritizedTile(tile, priority_rect_type_);
   return true;
 }