Cache viewport rect for tile priority in UpdateTiles
PictureLayerImpls in a tree should continue using the same viewport rect
for tile priority until UpdateTiles() is called with the new value of
viewport rect for tile priority. Otherwise, a PictureLayerImpl could be
in an inconsistent state that could lead to a wrong decision about
AllTilesRequiredForActivationAreReadyToDraw.
This CL caches the viewport rect for tile priority in PictureLayerImpl.
BUG= 449008
Review URL: https://codereview.chromium.org/819643004
Cr-Commit-Position: refs/heads/master@{#312523}
5 files changed
