Allows menu host windows to be enumerated in DragTargetWindowFinder

ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.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/desktop_drag_drop_client_aurax11.h"
 
 #include <X11/Xatom.h>
 
 #include "base/event_types.h"
 #include "base/lazy_instance.h"
@@ skipping 40 matching lines @@
   "XdndAware",
   "XdndDrop",
   "XdndEnter",
   "XdndFinished",
   "XdndLeave",
   "XdndPosition",
   "XdndProxy",  // Proxy windows?
   kXdndSelection,
   "XdndStatus",
   "XdndTypeList",
+  "_NET_WM_WINDOW_TYPE_MENU",
   NULL
 };
 
 static base::LazyInstance<
     std::map< ::Window, views::DesktopDragDropClientAuraX11*> >::Leaky
         g_live_client_map = LAZY_INSTANCE_INITIALIZER;
 
 // Helper class to FindWindowFor which looks for a drag target under the
 // cursor.
 class DragTargetWindowFinder : public ui::EnumerateWindowsDelegate {
  public:
   DragTargetWindowFinder(XID ignored_icon_window,
+                         Atom menu_type_atom,
                          gfx::Point screen_loc)
       : ignored_icon_window_(ignored_icon_window),
         output_window_(None),
+        menu_type_atom_(menu_type_atom),
         screen_loc_(screen_loc) {
     ui::EnumerateTopLevelWindows(this);
   }
 
   virtual ~DragTargetWindowFinder() {}
 
   XID window() const { return output_window_; }
 
  protected:
   virtual bool ShouldStopIterating(XID window) OVERRIDE {
     if (window == ignored_icon_window_)
       return false;
 
     if (!ui::IsWindowVisible(window))
       return false;
 
     if (!ui::WindowContainsPoint(window, screen_loc_))
       return false;
 
-    if (ui::PropertyExists(window, "WM_STATE")) {
+    int value = 0;
+    if (ui::PropertyExists(window, "WM_STATE") ||
+        (ui::GetIntProperty(window, "_NET_WM_WINDOW_TYPE", &value) &&
+         static_cast<Atom>(value) == menu_type_atom_)) {
       output_window_ = window;
       return true;
     }
 
     return false;
   }
 
  private:
   XID ignored_icon_window_;
   XID output_window_;
+  const Atom menu_type_atom_;
   gfx::Point screen_loc_;
 
   DISALLOW_COPY_AND_ASSIGN(DragTargetWindowFinder);
 };
 
 // Returns the topmost X11 window at |screen_point| if it is advertising that
 // is supports the Xdnd protocol. Will return the window under the pointer as
 // |mouse_window|. If there's a Xdnd aware window, it will be returned in
 // |dest_window|.
 void FindWindowFor(const gfx::Point& screen_point,
-                   ::Window* mouse_window, ::Window* dest_window) {
-  DragTargetWindowFinder finder(None, screen_point);
+                   ::Window* mouse_window, ::Window* dest_window,
+                   Atom menu_type_atom) {
+  DragTargetWindowFinder finder(None, menu_type_atom, screen_point);
   *mouse_window = finder.window();
   *dest_window = None;
 
   if (finder.window() == None)
     return;
 
   // Figure out which window we should test as XdndAware. If mouse_window has
   // XdndProxy, it will set that proxy on target, and if not, |target|'s
   // original value will remain.
   XID target = *mouse_window;
@@ skipping 288 matching lines @@
 
   // Mark that we are aware of drag and drop concepts.
   unsigned long xdnd_version = kMinXdndVersion;
   XChangeProperty(xdisplay_, xwindow_, atom_cache_.GetAtom("XdndAware"),
                   XA_ATOM, 32, PropModeReplace,
                   reinterpret_cast<unsigned char*>(&xdnd_version), 1);
 }
 
 DesktopDragDropClientAuraX11::~DesktopDragDropClientAuraX11() {
   g_live_client_map.Get().erase(xwindow_);
+  // Make sure that all observers are unregistered from source and target
+  // windows. This may be necessary when the parent native widget gets destroyed
+  // while a drag operation is in progress.
+  NotifyDragLeave();
+  target_current_context_.reset();
 }
 
 // static
 DesktopDragDropClientAuraX11* DesktopDragDropClientAuraX11::GetForWindow(
     ::Window window) {
   std::map< ::Window, DesktopDragDropClientAuraX11*>::const_iterator it =
       g_live_client_map.Get().find(window);
   if (it == g_live_client_map.Get().end())
     return NULL;
   return it->second;
@@ skipping 224 matching lines @@
   DCHECK_EQ(target_window_, window);
   target_window_ = NULL;
 }
 
 void DesktopDragDropClientAuraX11::OnMouseMovement(XMotionEvent* event) {
   gfx::Point screen_point(event->x_root, event->y_root);
 
   // Find the current window the cursor is over.
   ::Window mouse_window = None;
   ::Window dest_window = None;
-  FindWindowFor(screen_point, &mouse_window, &dest_window);
+  FindWindowFor(screen_point, &mouse_window, &dest_window,
+                atom_cache_.GetAtom("_NET_WM_WINDOW_TYPE_MENU"));
 
   if (source_current_window_ != dest_window) {
     if (source_current_window_ != None)
       SendXdndLeave(source_current_window_);
 
     source_current_window_ = dest_window;
 
     if (source_current_window_ != None) {
       negotiated_operation_.erase(source_current_window_);
       SendXdndEnter(source_current_window_);
@@ skipping 279 matching lines @@
   // GdkEvent about the failed drag. (And sending this message doesn't appear
   // to go through normal xlib machinery, but instead passes through the low
   // level xProto (the x11 wire format) that I don't understand.
   //
   // I'm unsure if I have to jump through those hoops, or if XSendEvent is
   // sufficient.
   XSendEvent(xdisplay_, xid, False, 0, xev);
 }
 
 }  // namespace views