Delete the property returned by SelectionNotify as per ICCCM spec

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 603 matching lines @@
   xev.xclient.window = source_window;
   xev.xclient.data.l[0] = xwindow_;
   xev.xclient.data.l[1] = (drag_operation != 0) ? 1 : 0;
   xev.xclient.data.l[2] = DragOperationToAtom(drag_operation);
 
   SendXClientEvent(source_window, &xev);
 }
 
 void DesktopDragDropClientAuraX11::OnSelectionNotify(
     const XSelectionEvent& xselection) {
-  if (!target_current_context_) {
-    NOTIMPLEMENTED();
-    return;
-  }
+  if (target_current_context_)
+    target_current_context_->OnSelectionNotify(xselection);
 
-  target_current_context_->OnSelectionNotify(xselection);
+  // ICCCM requires us to delete the property passed into SelectionNotify.
+  if (xselection.property != None)
+    XDeleteProperty(xdisplay_, xwindow_, xselection.property);
 }
 
 int DesktopDragDropClientAuraX11::StartDragAndDrop(
     const ui::OSExchangeData& data,
     aura::Window* root_window,
     aura::Window* source_window,
     const gfx::Point& root_location,
     int operation,
     ui::DragDropTypes::DragEventSource source) {
   source_current_window_ = None;
@@ skipping 404 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