Make parent permission dialog view not draggable

Draggability was never part of the requirements, and making this
dialog draggable results in a visual glitch where the dialog
appears (but isn't actuallly) duplicated when switching from
laptop to tablet mode.

Bug: 1072049
Change-Id: I1a1eeae93d1c4c537131371e05531a1fa2c553b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2209550Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Dan S <danan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#770387}

chrome/browser/ui/views/parent_permission_dialog_view.cc

@@ -268,7 +268,6 @@ ParentPermissionDialogView::ParentPermissionDialogView(
     ParentPermissionDialogView::Observer* observer)
     : params_(std::move(params)), observer_(observer) {
   SetDefaultButton(ui::DIALOG_BUTTON_OK);
-  set_draggable(true);
   SetButtonLabel(
       ui::DIALOG_BUTTON_OK,
       l10n_util::GetStringUTF16(IDS_PARENT_PERMISSION_PROMPT_APPROVE_BUTTON));