Bug 1397403 - Fix TabChild::GetActiveTabs comment (r=froydnj)

    return sActiveTabs && !sActiveTabs->IsEmpty();

  }

  // Returns whichever TabChild is currently in the foreground. If there are

  // multiple TabChilds in the foreground (due to multiple windows being open),

  // this returns null. This should only be called if HasActiveTabs() returns

  // true.

  // Returns the set of TabChilds that are currently in the foreground. There

  // can be multiple foreground TabChilds if Firefox has multiple windows

  // open. There can also be zero foreground TabChilds if the foreground tab is

  // in a different content process. Note that this function should only be

  // called if HasActiveTabs() returns true.

  static const nsTArray<TabChild*>& GetActiveTabs()

  {

    MOZ_ASSERT(HasActiveTabs());