fix tab-dragging with touch on immersive-mode for Mash

Things are really complicated when a tab is about to be dragged
with touch events during immersive fullscreen mode in Mash. The
details are depicted as
https://docs.google.com/document/d/1fS6YlkYUCqPCHJpVvKEVbgVilkmnPGl5x2a2kZvW7z0/edit?usp=sharing.

This CL allows Ash to pick up the right target window by setting
the insets when the reveal status is changed.

The test also needs to be fixed because:
- without reveal lock, it can't say the tabstrip is really there
  (and the insets are properly set)
- QuitWhenNotDragging needs to be executed for touch events too,
  otherwise it doesn't wait for asynchronous touch events.

Bug: 901544
Test: see the filter. also manually checked the behavior
Change-Id: I9215fd0198f48a0ac641cd850ff290513e185775
Reviewed-on: https://chromium-review.googlesource.com/c/1336370
Commit-Queue: Jun Mukai <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Cr-Commit-Position: refs/heads/master@{#612576}
12 files changed