Add travis-ci support

Add travis-ci support

We've been using drone.io as the continuous integration service, but
Chrome is no longer supported on Ubuntu 12.04, which is the only
convenient option there.

Bump minimum version required for Chrome to 49 due to revision 84cfcd2.
Some tests about image size would fail in version 46, but work in 49.

Chrome also dropped 32-bit support, so specify 64-bit version for apt.

BUG=604177
R=mdjones@chromium.org

Committed: c3edb386a994b246b4dacd1d40dd0c576df581fc

[wychen, 2016-04-17 08:41:27]

wychen@chromium.org changed reviewers:
+ mdjones@chromium.org

[wychen, 2016-04-17 08:41:28]

ptal

[mdjones, 2016-04-19 16:16:04]

lgtm

[wychen, 2016-04-19 18:06:33]

Description was changed from

==========
Add travis-ci support

We've been using drone.io as the continuous integration service, but
Chrome is no longer supported on Ubuntu 12.04, which is the only
convenient option there.

Bump minimum version required for Chrome to 49 due to revision 84cfcd2.
Some tests about image size would fail in version 46, but work in 49.

Chrome also dropped 32-bit support, so specify 64-bit version for apt.

BUG=604177
==========

to

==========
Add travis-ci support

We've been using drone.io as the continuous integration service, but
Chrome is no longer supported on Ubuntu 12.04, which is the only
convenient option there.

Bump minimum version required for Chrome to 49 due to revision 84cfcd2.
Some tests about image size would fail in version 46, but work in 49.

Chrome also dropped 32-bit support, so specify 64-bit version for apt.

BUG=604177
R=mdjones@chromium.org

Committed: c3edb386a994b246b4dacd1d40dd0c576df581fc
==========

[wychen, 2016-04-19 18:06:34]

Committed patchset #2 (id:20001) manually as
c3edb386a994b246b4dacd1d40dd0c576df581fc (presubmit successful).