Implement ViewsNSWindowDelegate::windowShouldClose

This to fix application menu Close Window for mac views like
-- save info to restore closed window
-- check onbeforeunload event

Bug: 751018
Change-Id: I7a99def820f066fc1f47c3c2bae3a2abb49106ff
Reviewed-on: https://chromium-review.googlesource.com/591848
Commit-Queue: Boris Yusupov <boriay@yandex-team.ru>
Reviewed-by: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491457}

ui/views/cocoa/views_nswindow_delegate.mm

@@ -92,6 +92,12 @@
   parent_->OnWindowKeyStatusChangedTo(false);
 }
 
+- (BOOL)windowShouldClose:(id)sender {
+  views::NonClientView* nonClientView =
+      [self nativeWidgetMac]->GetWidget()->non_client_view();
+  return !nonClientView || nonClientView->CanClose();
+}
+
 - (void)windowWillClose:(NSNotification*)notification {
   // Retain |self|. |parent_| should be cleared. OnWindowWillClose() may delete
   // |parent_|, but it may also dealloc |self| before returning. However, the

ui/views/widget/native_widget_mac_unittest.mm

@@ -915,11 +915,17 @@ class ModalDialogDelegate : public DialogDelegateView {
   explicit ModalDialogDelegate(ui::ModalType modal_type)
       : modal_type_(modal_type) {}
 
+  void set_can_close(bool value) { can_close_ = value; }
+
   // WidgetDelegate:
   ui::ModalType GetModalType() const override { return modal_type_; }
 
+  // DialogDelegate:
+  bool Close() override { return can_close_; }
+
  private:
   const ui::ModalType modal_type_;
+  bool can_close_ = true;
 
   DISALLOW_COPY_AND_ASSIGN(ModalDialogDelegate);
 };
@@ -1877,6 +1883,19 @@ TEST_F(NativeWidgetMacViewsOrderTest, UnassociatedViewsIsAbove) {
   ]]));
 }
 
+// Test -[NSWindowDelegate windowShouldClose:].
+TEST_F(NativeWidgetMacTest, CanClose) {
+  ModalDialogDelegate* delegate = new ModalDialogDelegate(ui::MODAL_TYPE_NONE);
+  Widget* widget =
+      views::DialogDelegate::CreateDialogWidget(delegate, nullptr, nullptr);
+  NSWindow* window = widget->GetNativeWindow();
+  delegate->set_can_close(false);
+  EXPECT_FALSE([[window delegate] windowShouldClose:window]);
+  delegate->set_can_close(true);
+  EXPECT_TRUE([[window delegate] windowShouldClose:window]);
+  widget->CloseNow();
+}
+
 }  // namespace test
 }  // namespace views