cc: Do not cleanup tiles with raster tasks.

cc/resources/prioritized_tile_set.cc

 // Copyright 2013 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_set.h"
 
 #include <algorithm>
 
 #include "cc/resources/managed_tile_state.h"
 #include "cc/resources/tile.h"
@@ skipping 63 matching lines @@
   bin_sorted_[bin] = false;
 }
 
 void PrioritizedTileSet::Clear() {
   for (int bin = 0; bin < NUM_BINS; ++bin) {
     tiles_[bin].clear();
     bin_sorted_[bin] = true;
   }
 }
 
+bool PrioritizedTileSet::IsEmpty() {
+  for (int bin = 0; bin < NUM_BINS; ++bin)
+    if (!tiles_[bin].empty())
+      return false;
+
+  return true;
+}
+
 void PrioritizedTileSet::SortBinIfNeeded(ManagedTileBin bin) {
   if (!bin_sorted_[bin]) {
     SortBinTiles(bin, &tiles_[bin]);
     bin_sorted_[bin] = true;
   }
 }
 
 PrioritizedTileSet::Iterator::Iterator(
     PrioritizedTileSet* tile_set, bool use_priority_ordering)
     : tile_set_(tile_set),
@@ skipping 37 matching lines @@
     if (use_priority_ordering_)
       tile_set_->SortBinIfNeeded(current_bin_);
 
     iterator_ = tile_set_->tiles_[current_bin_].begin();
     if (iterator_ != tile_set_->tiles_[current_bin_].end())
       break;
   }
 }
 
 }  // namespace cc