Reland "Prevent restoring focus when the EndDrag minimizes the window""

Some gesture may minimize the window along with ending the drag,
but TabDragController::RestoreFocus in EndDragImpl() cancels
the minimization.

Previous CL was reverted due to test failures on release bot,
because sequence of touch events may not generate fling gesture
if it moves too fast. This CL introduces SimpleTestTickClock to
generate the fling gesture reliably.

TBR=sky@chromium.org

Bug: 902897
Test: the new test case
Change-Id: I37cf7ce83a25d3fafbc9628515bae4c4185dabd6
Reviewed-on: https://chromium-review.googlesource.com/c/1379191
Reviewed-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@{#616922}
3 files changed