Revert 223324 "Wait for store flush in CookieMonster::Delete*Task"

ExtensionApiTest.CookiesEvents is failing intermittently, so reverting this
change.

> Wait for store flush in CookieMonster::Delete*Task
> 
> BUG=252217
> 
> Review URL: https://chromiumcodereview.appspot.com/18032002

TBR=philipj@opera.com,erikwright@chromium.org

Review URL: https://codereview.chromium.org/23530062

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@223359 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed