Retrieve per host storage usage from QuotaManager.

R=kinuko@chromium.org
BUG=none
TEST=QuotaManagerTest.GetUsage

Review URL: http://codereview.chromium.org/8079004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@103921 0039d316-1c4b-4281-b951-d872f2087c98
 void UsageTracker::GetCachedOrigins(std::set<GURL>* origins) const {
   DCHECK(origins);
   origins->clear();
  for (ClientTrackerMap::const_iterator iter = client_tracker_map_.begin();
       iter != client_tracker_map_.end(); ++iter) {
    iter->second->GetCachedOrigins(origins);
  }
}

 void UsageTracker::GetCachedOrigins(std::set<GURL>* origins) const {
   DCHECK(origins);
   origins->clear();
  for (ClientTrackerMap::const_iterator iter = client_tracker_map_.begin();
       iter != client_tracker_map_.end(); ++iter) {
    iter->second->GetCachedOrigins(origins);
  }
}
