Update the remaining include paths of base/string_piece.h to its new location.

webkit/tools/test_shell/test_shell_gtk.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 "webkit/tools/test_shell/test_shell.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <fontconfig/fontconfig.h>
 #include <gtk/gtk.h>
 #include <signal.h>
 #include <unistd.h>
 
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/message_loop.h"
 #include "base/path_service.h"
 #include "base/string16.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 #include "base/utf_string_conversions.h"
 #include "grit/test_shell_resources.h"
 #include "grit/webkit_resources.h"
 #include "net/base/mime_util.h"
 #include "net/base/net_util.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebPoint.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
 #include "ui/base/gtk/gtk_compat.h"
 #include "ui/base/layout.h"
@@ skipping 546 matching lines @@
     case IDR_BROKENIMAGE:
       resource_id = IDR_BROKENIMAGE_TESTSHELL;
       break;
     case IDR_TEXTAREA_RESIZER:
       resource_id = IDR_TEXTAREA_RESIZER_TESTSHELL;
       break;
   }
   // TODO(flackr): Pass scale_factor.
   return TestShell::ResourceProvider(resource_id);
 }