Use a direct include of strings headers in ui/, part 1.

ui/base/keycodes/keyboard_code_conversion_x.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/keycodes/keyboard_code_conversion_x.h"
 
 #define XK_3270  // for XK_3270_BackTab
 #include <X11/keysym.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 #include <X11/XF86keysym.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 
 namespace ui {
 
 // Get an ui::KeyboardCode from an X keyevent
 KeyboardCode KeyboardCodeFromXKeyEvent(XEvent* xev) {
   // XLookupKeysym does not take into consideration the state of the lock/shift
   // etc. keys. So it is necessary to use XLookupString instead.
   KeySym keysym;
   XLookupString(&xev->xkey, NULL, 0, &keysym, NULL);
@@ skipping 760 matching lines @@
     case VKEY_KBD_BRIGHTNESS_UP:
       return XF86XK_KbdBrightnessUp;
 
     default:
       LOG(WARNING) << "Unknown keycode:" << keycode;
       return 0;
     }
 }
 
 }  // namespace ui