CCA: Add a callback for gif mode to stop the capturing loop.

When minimizing CCA, the callback registered to
requestVideoFrameCallback will never run. In this case, the capturing
loop doesn't know the recording state is changed and will not
leave the loop then resolve the promise. The CL lets video mode
controller holds a callback which can stop the loop and it will be
invoked when stop() is invoked.

Bug: b:309901983
Test: Manually click stop button, wait for timer while capturing gif.
Test: Manually unplug external camera while while capturing gif.
Change-Id: I9c9a6655608b6f543c4c1af488adcf678da11535
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5072612
Commit-Queue: Sean Li <seannli@google.com>
Reviewed-by: Pi-Hsun Shih <pihsun@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1234458}