Break path whereby AssociatedURLLoader::~AssociatedURLLoader() is re-entered on top of itself.

BUG=159429

Review URL: https://chromiumcodereview.appspot.com/11359222

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@168150 0039d316-1c4b-4281-b951-d872f2087c98
void PPB_URLLoader_Impl::RunCallback(int32_t result) {
  if (!pending_callback_.get()) {
    CHECK(main_document_loader_);
    return;
  }

  DCHECK(!user_buffer_);

  user_buffer_ = NULL;
  user_buffer_size_ = 0;
  pending_callback_->Run(result);
}

void PPB_URLLoader_Impl::RunCallback(int32_t result) {
  if (!pending_callback_.get()) {
    CHECK(main_document_loader_);
    return;
  }

  DCHECK(!user_buffer_);

  user_buffer_ = NULL;
  user_buffer_size_ = 0;
  pending_callback_->Run(result);
}
