cc: Clear checker-image tracking on navigation and visibility changes.

cc/trees/layer_tree_host.h

 // Copyright 2011 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.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 606 matching lines @@
   // This is true if atleast one layer in the layer tree has a copy request. We
   // use this bool to decide whether we need to compute subtree has copy request
   // for every layer during property tree building.
   bool has_copy_request_ = false;
 
   MutatorHost* mutator_host_;
 
   std::vector<std::pair<sk_sp<const SkImage>, base::Callback<void(bool)>>>
       queued_image_decodes_;
 
-  bool did_navigate_ = false;
-
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_