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 QuotaManager::NotifyOriginNoLongerInUse(const GURL& origin) {
  DCHECK(io_thread_->BelongsToCurrentThread());
  DCHECK(IsOriginInUse(origin));
  int& count = origins_in_use_[origin];
  if (--count == 0)
    origins_in_use_.erase(origin);
}

void QuotaManager::NotifyOriginNoLongerInUse(const GURL& origin) {
  DCHECK(io_thread_->BelongsToCurrentThread());
  DCHECK(IsOriginInUse(origin));
  int& count = origins_in_use_[origin];
  if (--count == 0)
    origins_in_use_.erase(origin);
}
