capture_mode: Properly handle display rotation and bounds change.

For all modes for either rotation/bounds change:
  - End current drag
  - Redraw capture session layer
  - Reposition capture label and capture bar

Additionally for region:
  - Reset selection region if rotation changes
  - Clamp the selection region to root window bounds if size changes

Also fixes a bug where the user can select a large region on a display,
exit and then enter capture mode on a smaller display. This CL will
ensure the initial region is clamped to size of the smaller display.

Fixed: 1154465
Test: manual + added
Change-Id: I4dde6b97af9532d08f7e53348d7a8a28c0c38714
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2568669
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834529}