[sync] Add hooks to allow for testing sync credential caching in the presence of strange singleton …

[sync] Add hooks to allow for testing sync credential caching in the presence of strange singleton mode

Sync credential caching is currently broken by strange singleton mode, due to the fact that the metro and desktop directories are collapsed into one.

This patch adds test hooks to CredentialCacheService, to allow for its testing using two side-by-side instances of Desktop Chrome, one using the default desktop user data directory, and the other using what used to be the default metro user data directory.

Note that in order to enable these test hooks, the --enable-sync-credential-caching flag will have to be used. If the flag is not used, there will be no change in behavior, and strange singleton mode will continue to work as designed.

TBR=thakis@chromium.org
BUG=144280
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=153105

[Raghu Simha, 2012-08-22 22:26:36]

Carlos/Tim, please review. Thanks.

[cpu_(ooo_6.6-7.5), 2012-08-23 02:57:35]

lgtm on chrome_paths_win.cc

[Raghu Simha, 2012-08-23 20:53:00]

Tim, could you take a look when you get a chance?

[Raghu Simha, 2012-08-23 22:58:03]

Tim is sheriff today. Paging Nicolas :)

[Nicolas Zea, 2012-08-23 23:05:44]

lgtm

[Raghu Simha, 2012-08-23 23:34:36]

+thakis for OWNERS approval of chrome_paths_win.cc. Changes already reviewed by
cpu.

[Nico, 2012-08-23 23:48:16]

what lgtcpu lgtm