Exposes more mutation functions to MotionEventGeneric

Exposes more mutation functions to MotionEventGeneric

I want to keep around a MotionEventGeneric and mutate it over
time. Since this class is an implementation detail (public API takes
MotionEvent) it seems fine to allow consumers of it to mutate it
directly.

BUG=none
TEST=covered by test
R=tdresser@chromium.org

Committed: https://crrev.com/f1eb0a7e1062b0ea684727df4d61c55a75fe4a87
Cr-Commit-Position: refs/heads/master@{#322218}

[tdresser, 2015-03-25 18:38:03]

On 2015/03/25 18:23:40, sky wrote:

LGTM.

I'm not super fond of enabling mutation of MotionEventAura (which inherits from
MotionEventGeneric), but I don't think its a big deal. We do pass around
MotionEventAura a bit (through GestureProviderAura and GestureRecognizerImpl).

Out of curiosity, where will you be using these methods?

[sky, 2015-03-25 19:15:53]

This will be used in html_viewer.

[sky, 2015-03-25 19:15:58]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2015-03-25 19:17:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1035793003/1

[commit-bot: I haz the power, 2015-03-25 19:52:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-25 19:53:35]

Patchset 1 (id:??) landed as
https://crrev.com/f1eb0a7e1062b0ea684727df4d61c55a75fe4a87
Cr-Commit-Position: refs/heads/master@{#322218}