Prefix string16 with base:: in ui/.

ui/views/examples/multiline_example.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_EXAMPLES_MULTILINE_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_MULTILINE_EXAMPLE_H_
 
 #include "base/compiler_specific.h"
 #include "base/strings/string16.h"
 #include "ui/views/controls/button/checkbox.h"
@@ skipping 18 matching lines @@
   virtual void CreateExampleView(View* container) OVERRIDE;
 
   // ButtonListener:
   virtual void ButtonPressed(Button* sender, const ui::Event& event) OVERRIDE;
 
  private:
   class RenderTextView;
 
   // TextfieldController:
   virtual void ContentsChanged(Textfield* sender,
-                               const string16& new_contents) OVERRIDE;
+                               const base::string16& new_contents) OVERRIDE;
   virtual bool HandleKeyEvent(Textfield* sender,
                               const ui::KeyEvent& key_event) OVERRIDE;
 
   RenderTextView* render_text_view_;
   Label* label_;
   Textfield* textfield_;
 
   // Checkbox to enable and disable text rendering in |label_|.
   Checkbox* label_checkbox_;
 
   DISALLOW_COPY_AND_ASSIGN(MultilineExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_MULTILINE_EXAMPLE_H_