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::ButtonPressed(
    views::Button* sender, const ui::Event& event) {
  ToggleDetailLevel();
}

void ExpandableContainerView::ButtonPressed(
    views::Button* sender, const ui::Event& event) {
  ToggleDetailLevel();
}
