implement the logic to set tile priorities based on current matrix

cc/picture_layer_tiling_set.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/picture_layer_tiling_set.h"
 
 namespace cc {
 
 PictureLayerTilingSet::PictureLayerTilingSet(
     PictureLayerTilingClient * client)
@@ skipping 139 matching lines @@
   }
 
   return *this;
 }
 
 PictureLayerTilingSet::Iterator::operator bool() const {
   return current_tiling_ < static_cast<int>(set_->tilings_.size()) ||
       region_iter_.has_rect();
 }
 
+void PictureLayerTilingSet::UpdateTilePriorities(
+    const gfx::Size& view_port,
+    const gfx::Transform& last_transform,
+    const gfx::Transform& current_transform,
+    double time_delta) {
+  for (size_t i = 0; i < tilings_.size(); ++i) {
+    tilings_[i]->UpdateTilePriorities(
+        view_port, last_transform, current_transform, time_delta);
+  }
+}
+
 }  // namespace cc