Fix races in DeviceLocalAccountTest.Extensions*

Fix races in DeviceLocalAccountTest.Extensions*

The DeviceLocalAccountTest.Extensions* assumed that extensions get copied
to an account's cache after successful installation. In reality,
extensions are downloaded to the cache at first and then removed again if
installation fails. The removal happens asynchronously on a background
thread. This led to a race where tests would try to verify that an
extension does not exist in a cache without waiting for the removal
process to finish first.

This CL switches the tests from verifying that an extension has been
removed from disk to checking whether the cache entry has been removed,
which happens synchronously on the UI thread.

BUG=393208
TEST=DeviceLocalAccountTest.Extensions*

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285070

[bartfab (slow), 2014-07-14 12:55:42]

Hi Dmitry,

Could you review please?

Hi Zel,

Could you do an owner review for:
device_local_account_external_policy_loader.*

[Dmitry Polukhin, 2014-07-14 14:43:45]

lgtm

[bartfab (slow), 2014-07-23 08:30:17]

Hi Toni,

I am having no luck reaching Zel. Could you do an owner review for:

device_local_account_external_policy_loader.*

[Dmitry Polukhin, 2014-07-23 09:34:51]

lgtm

[tbarzic, 2014-07-23 15:18:18]

On 2014/07/23 09:34:51, Dmitry Polukhin wrote:
lgtm

[bartfab (slow), 2014-07-23 15:20:17]

The CQ bit was checked by bartfab@chromium.org

[commit-bot: I haz the power, 2014-07-23 15:21:23]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/bartfab@chromium.org/389313003/20001

[commit-bot: I haz the power, 2014-07-23 17:12:51]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)

[commit-bot: I haz the power, 2014-07-23 17:33:11]

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

[commit-bot: I haz the power, 2014-07-23 17:33:12]

Try jobs failed on following builders:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)

[bartfab (slow), 2014-07-23 17:40:22]

The CQ bit was checked by bartfab@chromium.org

[commit-bot: I haz the power, 2014-07-23 17:42:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/bartfab@chromium.org/389313003/20001

[commit-bot: I haz the power, 2014-07-23 22:59:41]

Change committed as 285070