Use a direct include of strings headers in content/browser/, part 2.

content/browser/web_contents/web_drag_source_gtk.h

 // 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.
 
 #ifndef CONTENT_BROWSER_WEB_CONTENTS_WEB_DRAG_SOURCE_GTK_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_DRAG_SOURCE_GTK_H_
 
 #include <gtk/gtk.h>
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/message_loop.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents.h"
 #include "googleurl/src/gurl.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebDragOperation.h"
 #include "ui/base/gtk/gtk_signal.h"
 #include "ui/base/gtk/gtk_signal_registrar.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/vector2d.h"
 
 class SkBitmap;
@@ skipping 82 matching lines @@
   GtkWidget* drag_icon_;
 
   ui::GtkSignalRegistrar signals_;
 
   DISALLOW_COPY_AND_ASSIGN(WebDragSourceGtk);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_DRAG_SOURCE_GTK_H_