cc: Add a tiling iterator that doesn't include borders

Resolve conflicts from https://codereview.chromium.org/202753002/
merged to WebView release branch.

Bug:13302269

Original description
cc: Add a tiling iterator that doesn't include borders

This iterator is needed to reland
https://codereview.chromium.org/196343005/ correctly, as whether or not
a set of picture tiles can raster a particular rect needs to ignore
borders.

BUG=353346
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=257688

Change-Id: I965befecd57c5fa470927143cc8f5de828e9e699
7 files changed