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
ClientUsageTracker* UsageTracker::GetClientTracker(QuotaClient::ID client_id) {
  ClientTrackerMap::iterator found = client_tracker_map_.find(client_id);
  if (found != client_tracker_map_.end())
    return found->second;
  return NULL;
}

ClientUsageTracker* UsageTracker::GetClientTracker(QuotaClient::ID client_id) {
  ClientTrackerMap::iterator found = client_tracker_map_.find(client_id);
  if (found != client_tracker_map_.end())
    return found->second;
  return NULL;
}
