Make shelf item can be dragged when context menu is opened.

ui/views/controls/menu/menu_controller.cc

Index: ui/views/controls/menu/menu_controller.cc
diff --git a/ui/views/controls/menu/menu_controller.cc b/ui/views/controls/menu/menu_controller.cc
index 7c44dd17258fde84b9059d4130ea94d1a111e8f6..38bfe809d91e9156801845abd098900e6296e564 100644
--- a/ui/views/controls/menu/menu_controller.cc
+++ b/ui/views/controls/menu/menu_controller.cc
@@ -820,9 +820,22 @@ void MenuController::OnGestureEvent(SubmenuView* source,
   if (event->stopped_propagation())
       return;
 
-  if (!part.submenu)
+  if (part.submenu) {
+    part.submenu->OnGestureEvent(event);
     return;
-  part.submenu->OnGestureEvent(event);
+  }
+
+#if !defined(OS_MACOSX)
+  if (preserve_current_gesture_for_owner()) {
+    event->ConvertLocationToTarget(source->GetWidget()->GetNativeWindow(),
+                                   owner()->GetNativeWindow());
+    owner()->OnGestureEvent(event);
+    // Reset |preserve_current_gesture_for_owner_| flag when the current gesture

[msw, 2017/06/01 20:24:27]

optional nit for one-liner:
  // Reset |preserve_current_gesture_for_owner_| when the first gesture ends.

[minch1, 2017/06/23 23:13:02]

Done.

+    // ends.
+    if (event->type() == ui::ET_GESTURE_END)
+      set_preserve_current_gesture_for_owner(false);

[msw, 2017/06/01 20:24:27]

optional nit: set the member directly instead of using the setter.

[minch1, 2017/06/23 23:13:02]

Done.

+  }
+#endif  // !defined(OS_MACOSX)
 }
 
 void MenuController::OnTouchEvent(SubmenuView* source, ui::TouchEvent* event) {
@@ -1376,27 +1389,8 @@ void MenuController::OnKeyDown(ui::KeyboardCode key_code) {
 MenuController::MenuController(bool blocking,
                                internal::MenuControllerDelegate* delegate)
     : blocking_run_(blocking),
-      showing_(false),
-      exit_type_(EXIT_NONE),
-      did_capture_(false),
-      result_(NULL),
-      accept_event_flags_(0),
-      drop_target_(NULL),
-      drop_position_(MenuDelegate::DROP_UNKNOWN),
-      owner_(NULL),
-      possible_drag_(false),
-      drag_in_progress_(false),
-      did_initiate_drag_(false),
-      valid_drop_coordinates_(false),
-      last_drop_operation_(MenuDelegate::DROP_UNKNOWN),
-      showing_submenu_(false),
       active_mouse_view_id_(ViewStorage::GetInstance()->CreateStorageID()),
-      hot_button_(nullptr),
-      delegate_(delegate),
-      is_combobox_(false),
-      item_selected_by_touch_(false),
-      current_mouse_event_target_(nullptr),
-      current_mouse_pressed_state_(0) {
+      delegate_(delegate) {
   delegate_stack_.push_back(delegate_);
   active_instance_ = this;
 }