GitLab

The hotseat affects the position of the PIP window, so this CL
includes the following changes to take it into consideration in
collision detection.

- Add the hotseat to collision rects. We adjust the bounds of the
  hotseat a bit so that we can slide the PIP window along the
  hotseat smoothly.
- Make hotseat state change trigger a system ui area change event
  in workspace layout manager.

Note we still have the PIP initial bounds issue as Android still
doesn't know the correct initial position.
BUG=b:147790853
TEST=Manually confirmed the PIP window was placed at the correct
TEST=position (once dragged) and was moved smoothly.
TEST=Manually confirmed toggling in-app state properly adjusted the
TEST=PIP window.

Change-Id: Idefc2877aa4aaf8996a016b64721bae4a74b3cea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2014357Reviewed-by: Mitsuru Oshima (slow in TOK) <oshima@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Kazuki Takise <takise@chromium.org>
Auto-Submit: Kazuki Takise <takise@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737243}