Input.dispatchTouchEvent sends events to SyntheticGestureController

In order to make the synthetic events sent from
Input.dispatchTouchEvent close to the native OS events, we should send
events to SyntheticGestureController, which will dispatch events to
each platform at a very low level.

Change-Id: Ic9ad2b0e3add91e8ce67c2b07f7dbaa5527c722b
Reviewed-on: https://chromium-review.googlesource.com/c/1428239
Reviewed-by: Joel Einbinder <einbinder@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
Commit-Queue: Lan Wei <lanwei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630973}
10 files changed