Inherits SupportsWeakPtr<T> instead of having WeakPtrFactory<T>

This change refines r137676.

BUG=122654
TEST=browser_test


Review URL: https://chromiumcodereview.appspot.com/10332233

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@139771 0039d316-1c4b-4281-b951-d872f2087c98
void ResourceDispatcherHostImpl::StartRequest(net::URLRequest* request) {
  request->Start();

  if (!update_load_states_timer_->IsRunning()) {
    update_load_states_timer_->Start(FROM_HERE,
        TimeDelta::FromMilliseconds(kUpdateLoadStatesIntervalMsec),
        this, &ResourceDispatcherHostImpl::UpdateLoadStates);
  }
}

void ResourceDispatcherHostImpl::StartRequest(net::URLRequest* request) {
  request->Start();

  if (!update_load_states_timer_->IsRunning()) {
    update_load_states_timer_->Start(FROM_HERE,
        TimeDelta::FromMilliseconds(kUpdateLoadStatesIntervalMsec),
        this, &ResourceDispatcherHostImpl::UpdateLoadStates);
  }
}
