Make SQLitePersistentCookieStore run on injected SequencedTaskRunners vs named BrowserThreads.

In a follow-up, I will make the production code run on the worker pool, which will hopefully speed up browser startup by eliminating delays due to other long-running DB thread tasks.

R=rdsmith@chromium.org
TBR=jar@chromium.org,mmenke@chromium.org
BUG=175415


Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=184868

Review URL: https://chromiumcodereview.appspot.com/12314015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@184879 0039d316-1c4b-4281-b951-d872f2087c98
7 files changed