Add new IDL for gamepad vibration

To support rumble effects via the Gamepad API, a new
GamepadHapticActuator interface is added. The actuator member
will be used to issue haptics commands to the associated gamepad.

BUG=749295

Change-Id: Ic6b6ecdfd13c8d7c263ec6dc2a8b3e44becf66a1
Reviewed-on: https://chromium-review.googlesource.com/695817
Commit-Queue: Matt Reynolds <mattreynolds@chromium.org>
Reviewed-by: Raymes Khoury <raymes@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512319}
16 files changed