Use thread with looper and native message loop for vsync service.

Use thread with looper and native message loop for vsync service.

This allows not to switch thread when communicating with the
choreographer.

This CL introduces NativeHandlerThread. This is a HandlerThread
(associated to an android Looper) that is also associated to a native
message loop to be able to receive mojo messages.

R=ppi@chromium.org
BUG=https://github.com/domokit/mojo/issues/535

Committed: https://chromium.googlesource.com/external/mojo/+/e15069cf509e8e2fe78200379d616b17eef81ece

[ppi, 2015-11-18 12:09:09]

lgtm

[qsr, 2015-11-18 12:59:32]

Committed patchset #1 (id:1) manually as
e15069cf509e8e2fe78200379d616b17eef81ece (presubmit successful).

[abarth, 2015-11-18 16:18:35]

abarth@google.com changed reviewers:
+ abarth@google.com

[abarth, 2015-11-18 16:18:35]

Thanks!