[Android] Clear application state on instrumentation test failure.

[Android] Clear application state on instrumentation test failure.

Some (still-unidentified) instrumentation tests leave an account on the
device, causing subsequent uses of the device to fail the DCHECK here:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/signin/oauth2_token_service_delegate_android.cc&l=552

Clearing the application state on failure should return the device to
a viable state.

This CL _does not_ resolve the underlying flake, but it does further
mitigate its impact while I keep looking for it.

BUG=533188
TBR=mikecase@chromium.org

Committed: https://crrev.com/150d81724c609b042dffacf1e770945b81673ac7
Cr-Commit-Position: refs/heads/master@{#353964}

[jbudorick, 2015-10-14 03:33:22]

TBR: limited-scope change to address flakiness P0

[jbudorick, 2015-10-14 03:33:29]

The CQ bit was checked by jbudorick@chromium.org

[commit-bot: I haz the power, 2015-10-14 03:34:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1407613004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1407613004/1

[commit-bot: I haz the power, 2015-10-14 05:56:13]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-14 05:56:58]

Patchset 1 (id:??) landed as
https://crrev.com/150d81724c609b042dffacf1e770945b81673ac7
Cr-Commit-Position: refs/heads/master@{#353964}

[mikecase (-- gone --), 2015-10-14 15:44:01]

lgtm, but why don't we always clear application state (on pass or failure)? And
is there any reason we didn't do this before (is it slow?).

[jbudorick, 2015-10-14 15:46:17]

On 2015/10/14 15:44:01, mikecase wrote:
> lgtm, but why don't we always clear application state (on pass or failure)?
And
> is there any reason we didn't do this before (is it slow?).

Yes, it is, and it's usually unnecessary.