Update the window shape when toggling whether the system titlebar and borders are used on KDE

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 331 matching lines @@
 
   desktop_native_widget_aura_->OnHostClosed();
 }
 
 aura::WindowTreeHost* DesktopWindowTreeHostX11::AsWindowTreeHost() {
   return this;
 }
 
 void DesktopWindowTreeHostX11::ShowWindowWithState(
     ui::WindowShowState show_state) {
-  if (!window_mapped_) {
+  if (!window_mapped_)
     MapWindow(show_state);
-    ResetWindowRegion();
-  }
 
   if (show_state == ui::SHOW_STATE_NORMAL ||
       show_state == ui::SHOW_STATE_MAXIMIZED) {
     // Note: XFCE ignores a maximize hint given before mapping the window.
     if (show_state == ui::SHOW_STATE_MAXIMIZED)
       Maximize();
     Activate();
   }
 
   native_widget_delegate_->AsWidget()->SetInitialFocus(show_state);
@@ skipping 901 matching lines @@
 }
 
 bool DesktopWindowTreeHostX11::HasWMSpecProperty(const char* property) const {
   return window_properties_.find(atom_cache_.GetAtom(property)) !=
       window_properties_.end();
 }
 
 void DesktopWindowTreeHostX11::SetUseNativeFrame(bool use_native_frame) {
   use_native_frame_ = use_native_frame;
   x11_window_event_filter_->SetUseHostWindowBorders(use_native_frame);
+  ResetWindowRegion();

[pkotwicz, 2014/06/10 22:00:53]

I am unsure if XShapeCombineRectangles() is safe to call on an unmapped window
in all window managers. If does not crash on either KDE or Cinnamon.

 }
 
 void DesktopWindowTreeHostX11::OnCaptureReleased() {
   x11_capture_.reset();
   g_current_capture = NULL;
   OnHostLostWindowCapture();
   native_widget_delegate_->OnMouseCaptureLost();
 }
 
 void DesktopWindowTreeHostX11::DispatchMouseEvent(ui::MouseEvent* event) {
@@ skipping 481 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