cc: Do not cleanup tiles with raster tasks.

cc/resources/tile.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/tile.h"
 
 #include <algorithm>
 
 #include "cc/base/math_util.h"
 #include "cc/debug/traced_value.h"
@@ skipping 83 matching lines @@
 
 RasterMode Tile::DetermineRasterModeForResolution(
     TileResolution resolution) const {
   RasterMode current_mode = managed_state_.raster_mode;
   RasterMode raster_mode = resolution == LOW_RESOLUTION
                                ? LOW_QUALITY_RASTER_MODE
                                : HIGH_QUALITY_RASTER_MODE;
   return std::min(raster_mode, current_mode);
 }
 
+bool Tile::HasRasterTask() const {
+  for (int mode = 0; mode < NUM_RASTER_MODES; ++mode) {
+    if (managed_state_.tile_versions[mode].raster_task_)
+      return true;
+  }
+  return false;
+}
+
 }  // namespace cc