Refactor ChooserDialogView to use borders instead of content margins.

chrome/browser/chooser_controller/chooser_controller.h

Index: chrome/browser/chooser_controller/chooser_controller.h
diff --git a/chrome/browser/chooser_controller/chooser_controller.h b/chrome/browser/chooser_controller/chooser_controller.h
index 33658c6ee8e405e567eb169f751bb35c030b7af3..4de65c104cab0e438f10582eae38604c5e4fb030 100644
--- a/chrome/browser/chooser_controller/chooser_controller.h
+++ b/chrome/browser/chooser_controller/chooser_controller.h
@@ -130,6 +130,9 @@ class ChooserController {
   void set_view(View* view) { view_ = view; }
   View* view() const { return view_; }
 
+ protected:
+  void set_title_for_testing(const base::string16& title) { title_ = title; }
+
  private:
   base::string16 title_;
   View* view_ = nullptr;