Add API to set clip rect on ui Layer

This patch adds API to ui::Layer to set clip rect. The clip rect clips
the subtree of the layer it is set on.

Bug: 951826
Change-Id: Idf136f16913288101cdee42346a55810432c6667
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1666746
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Malay Keshav <malaykeshav@chromium.org>
Cr-Commit-Position: refs/heads/master@{#670785}
2 files changed