Make the webstore inline install dialog be tab-modal

Also clean up a few minor lint errors while I'm in here.

BUG=550047

Review URL: https://codereview.chromium.org/1496033003

Cr-Commit-Position: refs/heads/master@{#363925}
void ExpandableContainerView::ToggleDetailLevel() {
  expanded_ = !expanded_;

  if (slide_animation_.IsShowing())
    slide_animation_.Hide();
  else
    slide_animation_.Show();
}

void ExpandableContainerView::ToggleDetailLevel() {
  expanded_ = !expanded_;

  if (slide_animation_.IsShowing())
    slide_animation_.Hide();
  else
    slide_animation_.Show();
}
