Backfill some UI tests.

ui/views/window/dialog_delegate_unittest.cc

Index: ui/views/window/dialog_delegate_unittest.cc
diff --git a/ui/views/window/dialog_delegate_unittest.cc b/ui/views/window/dialog_delegate_unittest.cc
index 59e46551ee5e8186d6a2d29e9030995ae016f0e7..f4993bd35e418ef5f3343e844bda799bd1cc212f 100644
--- a/ui/views/window/dialog_delegate_unittest.cc
+++ b/ui/views/window/dialog_delegate_unittest.cc
@@ -289,6 +289,19 @@ TEST_F(DialogTest, HitTest_WithTitle) {
   }
 }
 
+TEST_F(DialogTest, HitTest_CloseButton) {
+  const NonClientView* view = dialog()->GetWidget()->non_client_view();
+  dialog()->set_show_close_button(true);
+  BubbleFrameView* frame = static_cast<BubbleFrameView*>(view->frame_view());
+  frame->ResetWindowControls();
+
+  const gfx::Rect close_button_bounds =
+      frame->GetCloseButtonForTest()->bounds();
+  EXPECT_EQ(HTCLOSE,
+            frame->NonClientHitTest(gfx::Point(close_button_bounds.x() + 4,
+                                               close_button_bounds.y() + 4)));
+}
+
 TEST_F(DialogTest, BoundsAccommodateTitle) {
   TestDialog* dialog2(new TestDialog());
   dialog2->set_title(base::ASCIIToUTF16("Title"));