Allows menu host windows to be enumerated in DragTargetWindowFinder

ui/views/widget/desktop_aura/x11_desktop_handler.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/widget/desktop_aura/x11_desktop_handler.h"
 
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
 
 #include "base/message_loop/message_loop.h"
 #include "ui/aura/env.h"
 #include "ui/aura/window_event_dispatcher.h"
+#include "ui/base/x/x11_menu_list.h"
 #include "ui/base/x/x11_util.h"
+#include "ui/gfx/x/x11_error_tracker.h"
 
 #if !defined(OS_CHROMEOS)
 #include "ui/views/ime/input_method.h"
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h"
 #endif
 
 namespace {
 
 const char* kAtomsToCache[] = {
   "_NET_ACTIVE_WINDOW",
@@ skipping 107 matching lines @@
       if (event->xproperty.window == x_root_window_ &&
           event->xproperty.atom == active_window_atom) {
         ::Window window;
         if (ui::GetXIDProperty(x_root_window_, "_NET_ACTIVE_WINDOW", &window) &&
             window) {
           OnActiveWindowChanged(window);
         }
       }
       break;
     }
+    // Menus created by Chrome can be drag and drop targets. Since they are
+    // direct children of the screen root window and have override_redirect
+    // we cannot use regular _NET_CLIENT_LIST_STACKING property to find them
+    // and use a separate cache to keep track of them.
+    // TODO(varkha): Implement caching of all top level X windows and their
+    // coordinates and stacking order to eliminate repeated calls to X server
+    // during mouse movement, drag and shaping events.
+    case CreateNotify: {
+      // The window might be destroyed if the message pump haven't gotten a
+      // chance to run but we can safely ignore the X error.
+      gfx::X11ErrorTracker error_tracker;
+      XCreateWindowEvent *xcwe = &event->xcreatewindow;
+      ui::XMenuList::GetInstance()->MaybeRegisterMenu(xcwe->window);
+      break;
+    }
+    case DestroyNotify: {
+      XDestroyWindowEvent *xdwe = &event->xdestroywindow;
+      ui::XMenuList::GetInstance()->MaybeUnregisterMenu(xdwe->window);
+      break;
+    }
   }
 
   return POST_DISPATCH_NONE;
 }
 
 void X11DesktopHandler::OnWindowInitialized(aura::Window* window) {
 }
 
 void X11DesktopHandler::OnWillDestroyEnv() {
   g_handler = NULL;
@@ skipping 10 matching lines @@
 
   DesktopWindowTreeHostX11* new_host =
       views::DesktopWindowTreeHostX11::GetHostForXID(xid);
   if (new_host)
     new_host->HandleNativeWidgetActivationChanged(true);
 
   current_window_ = xid;
 }
 
 }  // namespace views