ui: Forward declare DefaultSingletonTraits in header files.

ui/base/touch/touch_factory.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/base/touch/touch_factory.h"
 
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/extensions/XIproto.h>
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
+#include "base/memory/singleton.h"
 #include "base/message_loop.h"
 #include "base/string_number_conversions.h"
 #include "base/string_split.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/base/x/x11_util.h"
 
 namespace {
 
 // The X cursor is hidden if it is idle for kCursorIdleSeconds seconds.
 int kCursorIdleSeconds = 5;
@@ skipping 387 matching lines @@
   else if (touch_device_available_)
     XDefineCursor(display, window, invisible_cursor_);
 }
 
 bool TouchFactory::IsTouchDevicePresent() {
   touch_present_called_ = true;
   return (touch_device_available_ && touch_events_allowed_);
 }
 
 }  // namespace ui