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When the touch events move very quickly on detaching, some
touch events are already queued, those queued touch events
aren't processed properly.

- Detach() aren't releasing the capture on the source widget.
  This means those queued touch events are targeted to the
  source widget instead of the moving widget, but the touch
  history is already transferred to the moving widget, which
  makes troubles on gesture recognition. We can release the
  capture on the detach on this specific situation.
- the recognized gestures are sent to the root window of
  the moving widget and nobody can handle. The new class
  RemainingGestureEventHandler handles them.
- RemainingGestureEventHandler should not handle events
  originated from ET_TOUCH_CANCELLED -- some test cases
  actually fail if so. ET_TOUCH_CANCELLED can happen internally
  within the browser (like Window::CleanupGestureState()),
  but that's not the intention of this class.

Bug: 943316
Test: the new test case in interactive_ui_tests
Change-Id: I679562d7707342874960dd7ff4d70d749f1ad437
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1545113Reviewed-by: Jun Mukai <mukai@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#647789}