Clear out some minor TODOs.

BUG=none

Review URL: https://codereview.chromium.org/1047063002

Cr-Commit-Position: refs/heads/master@{#322959}
void CardUnmaskPromptViews::ControllerGone() {
  controller_ = nullptr;
  ClosePrompt();
}

void CardUnmaskPromptViews::ControllerGone() {
  controller_ = nullptr;
  ClosePrompt();
}
