Fixes for touchpad capture

When touchpad capture is enabled, events still are received via
onGenericMotionEvent. As pointer capture sends events via
onCapturedPointerEvent, this patch changes the callback used by
captured touchpads to also be onCapturedPointerEvent.

Make events from a captured touchpad cause the device to leave touch
mode. Captured mice cause the device to exit touch mode through
the virtual dpad which is mapped to it due to being
derived from SOURCE_CLASS_TRACKBALL.

Test: Write an app that starts pointer capture on a device with a
      touchpad. Events from touchpad should be received via
      onCapturedPointerEvent.

Test: Using the captured touchpad in the first test should cause the
      view to be focusable even when not in touch mode.

Change-Id: If6fa94c66f1d9395a13fd5f31f642567256dd818