Prepare for -Wall for third-party code, -Wextra for chromium_code

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/Xatom.h>
 #include <X11/Xregion.h>
 #include <X11/Xutil.h>
 #include <X11/extensions/XInput2.h>
@@ skipping 1999 matching lines @@
   return gfx::ToEnclosingRect(rect_in_dip);
 }
 
 gfx::Rect DesktopWindowTreeHostX11::ToPixelRect(
     const gfx::Rect& rect_in_dip) const {
   gfx::RectF rect_in_pixels = gfx::RectF(rect_in_dip);
   GetRootTransform().TransformRect(&rect_in_pixels);
   return gfx::ToEnclosingRect(rect_in_pixels);
 }
 
-const XID DesktopWindowTreeHostX11::GetModalDialog() {
+XID DesktopWindowTreeHostX11::GetModalDialog() {
   return modal_dialog_xid_;
 }
 
 void DesktopWindowTreeHostX11::DisableEventListening(XID dialog) {
   DCHECK(dialog);
   DCHECK(!modal_dialog_xid_);
   modal_dialog_xid_ = dialog;
   // ScopedWindowTargeter is used to temporarily replace the event-targeter
   // with NullEventTargeter to make |dialog| modal.
   targeter_for_modal_.reset(new aura::ScopedWindowTargeter(window(),
@@ skipping 23 matching lines @@
   if (linux_ui) {
     ui::NativeTheme* native_theme = linux_ui->GetNativeTheme(window);
     if (native_theme)
       return native_theme;
   }
 
   return ui::NativeThemeAura::instance();
 }
 
 }  // namespace views