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::ClearLoginDelegateForRequest(
    net::URLRequest* request) {
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  if (info)
    info->set_login_delegate(NULL);
}

void ResourceDispatcherHostImpl::ClearLoginDelegateForRequest(
    net::URLRequest* request) {
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  if (info)
    info->set_login_delegate(NULL);
}
