Prefix string16 with base:: in ui/.

ui/views/linux_ui/linux_ui.h

 // Copyright 2013 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 UI_VIEWS_LINUX_UI_LINUX_UI_H_
 #define UI_VIEWS_LINUX_UI_LINUX_UI_H_
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/base/ime/linux/linux_input_method_context_factory.h"
 #include "ui/shell_dialogs/linux_shell_dialog.h"
@@ skipping 68 matching lines @@
   // progress, if available.
   virtual void SetDownloadCount(int count) const = 0;
   virtual void SetProgressFraction(float percentage) const = 0;
 
   // Checks for platform support for status icons.
   virtual bool IsStatusIconSupported() const = 0;
 
   // Create a native status icon.
   virtual scoped_ptr<StatusIconLinux> CreateLinuxStatusIcon(
       const gfx::ImageSkia& image,
-      const string16& tool_tip) const = 0;
+      const base::string16& tool_tip) const = 0;
 
   // Returns the icon for a given content type from the icon theme.
   // TODO(davidben): Add an observer for the theme changing, so we can drop the
   // caches.
   virtual gfx::Image GetIconForContentType(
       const std::string& content_type, int size) const = 0;
 
   // Notifies the observer about changes about how window buttons should be
   // laid out. If the order is anything other than the default min,max,close on
   // the right, will immediately send a button change event to the observer.
   virtual void AddWindowButtonOrderObserver(
       WindowButtonOrderObserver* observer) = 0;
 
   // Removes the observer from the LinuxUI's list.
   virtual void RemoveWindowButtonOrderObserver(
       WindowButtonOrderObserver* observer) = 0;
 
   // Determines whether the user's window manager is Unity.
   virtual bool UnityIsRunning() = 0;
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_LINUX_UI_LINUX_UI_H_