Fix possible map::end() dereference in AppCacheUpdateJob triggered by a compromised renderer.

BUG=551044

Review URL: https://codereview.chromium.org/1418783005

Cr-Commit-Position: refs/heads/master@{#358815}
void AppCacheHost::DoPendingGetStatus() {
  DCHECK_EQ(false, pending_get_status_callback_.is_null());

  pending_get_status_callback_.Run(GetStatus(), pending_callback_param_);
  pending_get_status_callback_.Reset();
  pending_callback_param_ = NULL;
}

void AppCacheHost::DoPendingGetStatus() {
  DCHECK_EQ(false, pending_get_status_callback_.is_null());

  pending_get_status_callback_.Run(GetStatus(), pending_callback_param_);
  pending_get_status_callback_.Reset();
  pending_callback_param_ = NULL;
}
