Allow menus to stay open during a child view's drag and drop

ui/views/controls/menu/menu_host.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/controls/menu/menu_host.h"
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "ui/events/gestures/gesture_recognizer.h"
 #include "ui/gfx/path.h"
@@ skipping 92 matching lines @@
 
 internal::RootView* MenuHost::CreateRootView() {
   return new MenuHostRootView(this, submenu_);
 }
 
 void MenuHost::OnMouseCaptureLost() {
   if (destroying_ || ignore_capture_lost_)
     return;
   MenuController* menu_controller =
       submenu_->GetMenuItem()->GetMenuController();
-  if (menu_controller && !menu_controller->drag_in_progress())
+  if (menu_controller &&
+      !menu_controller->drag_in_progress() &&
+      !dragged_view()) {

[sky, 2014/07/11 17:45:33]

Document why we check dragged_view(). I also midly prefer putting as much on one
line as possible, in other words merge 113 and 114.

[Devlin, 2014/07/11 18:43:51]

If we forward a OnDragWillStart() down to MenuController, I don't think we need
to check dragged view anymore, because drag_in_progress will actually be true
here.  Right?

[sky, 2014/07/11 19:15:20]

Yes, I believe you are right.

     menu_controller->CancelAll();
+  }
   Widget::OnMouseCaptureLost();
 }
 
 void MenuHost::OnNativeWidgetDestroyed() {
   if (!destroying_) {
     // We weren't explicitly told to destroy ourselves, which means the menu was
     // deleted out from under us (the window we're parented to was closed). Tell
     // the SubmenuView to drop references to us.
     submenu_->MenuHostDestroyed();
   }
   Widget::OnNativeWidgetDestroyed();
 }
 
 void MenuHost::OnOwnerClosing() {
   if (destroying_)
     return;
 
   MenuController* menu_controller =
       submenu_->GetMenuItem()->GetMenuController();
   if (menu_controller && !menu_controller->drag_in_progress())
     menu_controller->CancelAll();
 }
 
+void MenuHost::OnDragComplete() {
+  // During a view's drag, we may have lost the capture. Reset it so that we

[sky, 2014/07/11 17:45:33]

Add a delegate method as to what should happen when the drag is completed. The
default implementation should return a value indicating the menu should close.
WrenchMenu would return otherwise. This code should just call through to the
MenuController and let it do the right thing.

[Devlin, 2014/07/11 18:43:51]

Done.  However, this has a side-effect: other drags in the wrench menu (e.g.,
bookmarks) now behave differently than they used to.  Is this okay?

[sky, 2014/07/11 19:15:20]

Good point. I don't believe the bookmark code does the right thing in the cast,
so you should cancel on a drag from bookmarks. The delegate should only be
consulted on drags initiated outside of menu code.

[Devlin, 2014/07/11 20:28:15]

Tentatively done (see comment on new patch set).

+  // get OnMouseCaptureLost events.
+  native_widget_private()->SetCapture();
+}
+
 }  // namespace views