Only update icon if the new one is not null on x11, no-op for null icon (follow the same way as Win…

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.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_window_tree_host_x11.h"
 
 #include <X11/extensions/shape.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xregion.h>
@@ skipping 775 matching lines @@
   //
   // All of this could be made much, much better.
   std::vector<unsigned long> data;
 
   if (window_icon.HasRepresentation(1.0f))
     SerializeImageRepresentation(window_icon.GetRepresentation(1.0f), &data);
 
   if (app_icon.HasRepresentation(1.0f))
     SerializeImageRepresentation(app_icon.GetRepresentation(1.0f), &data);
 
-  if (data.empty())
-    XDeleteProperty(xdisplay_, xwindow_, atom_cache_.GetAtom("_NET_WM_ICON"));
-  else
+  if (!data.empty())
     ui::SetAtomArrayProperty(xwindow_, "_NET_WM_ICON", "CARDINAL", data);
 }
 
 void DesktopWindowTreeHostX11::InitModalType(ui::ModalType modal_type) {
   switch (modal_type) {
     case ui::MODAL_TYPE_NONE:
       break;
     default:
       // TODO(erg): Figure out under what situations |modal_type| isn't
       // none. The comment in desktop_native_widget_aura.cc suggests that this
@@ skipping 1176 matching lines @@
   if (linux_ui) {
     ui::NativeTheme* native_theme = linux_ui->GetNativeTheme(window);
     if (native_theme)
       return native_theme;
   }
 
   return ui::NativeTheme::instance();
 }
 
 }  // namespace views