Reset property tree indices when layer is removed from layer tree

cc/trees/property_tree.cc

 // Copyright 2014 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 <set>
 #include <vector>
 
 #include "base/logging.h"
 #include "cc/base/math_util.h"
 #include "cc/trees/property_tree.h"
@@ skipping 364 matching lines @@
   node->data.to_target.Translate(translation.x(), translation.y());
   node->data.from_target.matrix().postTranslate(-translation.x(),
                                                 -translation.y(), 0);
   node->data.to_screen.Translate(translation.x(), translation.y());
   node->data.from_screen.matrix().postTranslate(-translation.x(),
                                                 -translation.y(), 0);
 
   node->data.scroll_snap = translation;
 }
 
-PropertyTrees::PropertyTrees() : needs_rebuild(true) {
+PropertyTrees::PropertyTrees() : needs_rebuild(true), sequence_number(0) {
 }
 
 }  // namespace cc