Fix conditional disabling of flaky AutomationApiTest.Mixins

Fix conditional disabling of flaky AutomationApiTest.Mixins

Change https://codereview.chromium.org/1014543006 was supposed to disable
AutomationApiTest.Mixins because it is flaky (it fails ~8% of the time on
Windows, and is also flaky on Linux).

However the disabling didn't work because the newly created MAYBE_Mixins
macro is never used. This fixes that by renaming the test.

The line that always fails is:

assertEq(2, input.textSelStart);

The output is:

Actual: 0
Expected: 2

R=ellyjones@chromium.org
TBR=aboxhall@chromium.org
BUG=467921
Committed: https://crrev.com/4e2f4e9ea13d850e16f3aa2c5a9ee2273608f564
Cr-Commit-Position: refs/heads/master@{#330202}

[brucedawson, 2015-05-15 20:10:17]

Elly, can you take a look?

[Elly Fong-Jones, 2015-05-15 20:26:10]

lgtm

[brucedawson, 2015-05-15 20:29:14]

The CQ bit was checked by brucedawson@chromium.org

[commit-bot: I haz the power, 2015-05-15 20:31:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1129733004/1

[commit-bot: I haz the power, 2015-05-15 21:25:29]

Committed patchset #1 (id:1)

[brucedawson, 2015-05-16 00:01:26]

CCing csharp@ and maniscalco@ to close the loop.

[commit-bot: I haz the power, 2015-05-18 11:27:46]

Patchset 1 (id:??) landed as
https://crrev.com/4e2f4e9ea13d850e16f3aa2c5a9ee2273608f564
Cr-Commit-Position: refs/heads/master@{#330202}

[maniscalco, 2015-05-18 15:23:35]

On 2015/05/16 00:01:26, brucedawson wrote:
> CCing csharp@ and maniscalco@ to close the loop.

Good catch.