Clear out some minor TODOs.

BUG=none

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

Cr-Commit-Position: refs/heads/master@{#322959}
void CardUnmaskPromptViews::OnNativeThemeChanged(const ui::NativeTheme* theme) {
  SkColor bg_color =
      theme->GetSystemColor(ui::NativeTheme::kColorId_DialogBackground);
  progress_overlay_->set_background(
      views::Background::CreateSolidBackground(bg_color));
  progress_label_->SetBackgroundColor(bg_color);
}

void CardUnmaskPromptViews::OnNativeThemeChanged(const ui::NativeTheme* theme) {
  SkColor bg_color =
      theme->GetSystemColor(ui::NativeTheme::kColorId_DialogBackground);
  progress_overlay_->set_background(
      views::Background::CreateSolidBackground(bg_color));
  progress_label_->SetBackgroundColor(bg_color);
}
