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::RemovePendingRequest(int child_id,
                                                      int request_id) {
  PendingRequestList::iterator i = pending_requests_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_requests_.end()) {
    NOTREACHED() << "Trying to remove a request that's not here";
    return;
  }
  RemovePendingRequest(i);
}

void ResourceDispatcherHostImpl::RemovePendingRequest(int child_id,
                                                      int request_id) {
  PendingRequestList::iterator i = pending_requests_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_requests_.end()) {
    NOTREACHED() << "Trying to remove a request that's not here";
    return;
  }
  RemovePendingRequest(i);
}
