Deflake Device Orientation/Motion browsertests.

Deflake Device Orientation/Motion browsertests.

Currently Device Orientation/Motion null event tests with alert are
flaking on some windows and android bots. This patch splits the null
event tests into basic tests and one test with modal alert dialog.
The latter test ensures that the null events still arrive when active
dom objects are suspended (by alert).

BUG=360578
Committed: https://crrev.com/34feb66fd7cadba0b35504269cdaa923f79f210d
Cr-Commit-Position: refs/heads/master@{#316207}

[timvolodine, 2015-02-10 16:41:05]

timvolodine@chromium.org changed reviewers:
+ andrewhayden@chromium.org

[Andrew Hayden (chromium.org), 2015-02-12 14:53:50]

LGTM, but it wouldn't hurt my feelings to see a comment in the HTML for the
final alert-based test noting the reason for the alert in-situ.

[timvolodine, 2015-02-12 19:29:13]

New patchsets have been uploaded after l-g-t-m from andrewhayden@chromium.org

[timvolodine, 2015-02-12 19:40:32]

On 2015/02/12 14:53:50, Andrew Hayden wrote:
> LGTM, but it wouldn't hurt my feelings to see a comment in the HTML for the
> final alert-based test noting the reason for the alert in-situ.

thanks Andrew, done.

[timvolodine, 2015-02-12 19:44:59]

The CQ bit was checked by timvolodine@chromium.org

[commit-bot: I haz the power, 2015-02-12 19:46:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/870103004/40001

[commit-bot: I haz the power, 2015-02-12 21:03:52]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-02-12 21:03:52]

Try jobs failed on following builders:
  linux_chromium_chromeos_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[timvolodine, 2015-02-13 11:43:05]

The CQ bit was checked by timvolodine@chromium.org

[commit-bot: I haz the power, 2015-02-13 11:43:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/870103004/40001

[commit-bot: I haz the power, 2015-02-13 12:46:54]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-13 12:47:51]

Patchset 3 (id:??) landed as
https://crrev.com/34feb66fd7cadba0b35504269cdaa923f79f210d
Cr-Commit-Position: refs/heads/master@{#316207}