The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f9c42e188b9b4d4333b25ca75a7666c28695fce4

commit f9c42e188b9b4d4333b25ca75a7666c28695fce4
Author: khushalsagar <khushalsagar@chromium.org>
Date: Mon May 15 22:30:48 2017

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

Currently the tracker tracks decode policy for images across
navigations, which can significantly increase the size of the map
tracking this state. This change ensures that we clear this state on
navigations since the same image id should not be re-used. Also, it
ensures that we drop any cached decodes after navigations and a
memory policy update which evicts all resources.

BUG= 693228 ,  691080 
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2869513002
Cr-Commit-Position: refs/heads/master@{#471927}

[modify] https://crrev.com/f9c42e188b9b4d4333b25ca75a7666c28695fce4/cc/tiles/checker_image_tracker.cc
[modify] https://crrev.com/f9c42e188b9b4d4333b25ca75a7666c28695fce4/cc/tiles/checker_image_tracker.h
[modify] https://crrev.com/f9c42e188b9b4d4333b25ca75a7666c28695fce4/cc/tiles/checker_image_tracker_unittest.cc
[modify] https://crrev.com/f9c42e188b9b4d4333b25ca75a7666c28695fce4/cc/tiles/tile_manager.cc
[modify] https://crrev.com/f9c42e188b9b4d4333b25ca75a7666c28695fce4/cc/tiles/tile_manager.h
[modify] https://crrev.com/f9c42e188b9b4d4333b25ca75a7666c28695fce4/cc/trees/layer_tree_host.cc
[modify] https://crrev.com/f9c42e188b9b4d4333b25ca75a7666c28695fce4/cc/trees/layer_tree_host.h
[modify] https://crrev.com/f9c42e188b9b4d4333b25ca75a7666c28695fce4/cc/trees/layer_tree_host_impl.cc