MacViews: Protect against orderOut: on an NSWindow with an attached sheet.

ui/views/cocoa/widget_owner_nswindow_adapter.mm

Index: ui/views/cocoa/widget_owner_nswindow_adapter.mm
diff --git a/ui/views/cocoa/widget_owner_nswindow_adapter.mm b/ui/views/cocoa/widget_owner_nswindow_adapter.mm
index 5259c7e25b209c1288fc77dd7e7c171cba41fa78..b40ea57f523cfa5353fe51c5b4e5e388a8e34349 100644
--- a/ui/views/cocoa/widget_owner_nswindow_adapter.mm
+++ b/ui/views/cocoa/widget_owner_nswindow_adapter.mm
@@ -102,7 +102,11 @@ void WidgetOwnerNSWindowAdapter::OnWindowDidChangeOcclusionState() {
     return;
 
   if (child_->window_visible()) {
-    DCHECK([child_->ns_window() parentWindow]);
+    // A sheet should never have a parentWindow, otherwise dismissing the sheet
+    // causes graphical glitches (http://crbug.com/605098). Non-sheets should
+    // always have a parentWindow.
+    DCHECK([child_->ns_window() isSheet] !=

[karandeepb, 2016/11/28 05:19:32]

So this was/is slightly confusing. Is this correct:

For sheet BNW, the BNW->parent()->ns_window() refers to the NSWindow the sheet
is attached to. But the actual parentWindow property ([[BNW->ns_window()]
parentWindow]) for a sheet BNW should be nil?

For non-sheet windows, [BNW->ns_window() parentWindow]  ==
BNW->parent()->ns_window().

Using the same parent_ terminology for both cases is slightly confusing. Maybe
this can be clarified somewhere in bridged_native_widget.h.

[tapted, 2016/11/28 06:15:41]

yes. ([NSWindow parentWindow] should be nil -- but sheets also have [NSWindow
sheetParent])
yes (so long as the windows are visible)
I think the complexity is Cocoa's fault. The nicest thing we can do is probably
isolate the BridgedNativeWidget API from anything to do with NSWindow
parentWindow/sheetParent, and just manage write defensive code under the hood.

(also it's possible we'll drop sheets completely with the modality proposal, and
just use tab-modals that don't use sheets at all, but we need to keep this for a
bit longer so we aren't changing too much UX at once).

[karandeepb, 2016/11/28 23:37:57]

Acknowledged.

+           !![child_->ns_window() parentWindow]);
     DCHECK(child_->wants_to_be_visible());
     return;
   }
@@ -115,8 +119,8 @@ void WidgetOwnerNSWindowAdapter::OnWindowDidChangeOcclusionState() {
   [child_->ns_window() orderWindow:NSWindowAbove
                         relativeTo:[anchor_window_ windowNumber]];
 
-  // Ordering the window should add back the relationship.
-  DCHECK([child_->ns_window() parentWindow]);
+  // Ordering the window should add back the relationship (unless it's a sheet).
+  DCHECK([child_->ns_window() isSheet] != !![child_->ns_window() parentWindow]);
   DCHECK(child_->window_visible());
 }