Move more uses of string16 to specify base::

ui/base/ime/composition_text.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 UI_BASE_IME_COMPOSITION_TEXT_H_
 #define UI_BASE_IME_COMPOSITION_TEXT_H_
 
 #include "base/strings/string16.h"
 #include "ui/base/ime/composition_underline.h"
 #include "ui/base/ui_export.h"
@@ skipping 18 matching lines @@
     return true;
   }
 
   bool operator!=(const CompositionText& rhs) const {
     return !(*this == rhs);
   }
 
   void Clear();
 
   // Content of the composition text.
-  string16 text;
+  base::string16 text;
 
   // Underline information of the composition text.
   // They must be sorted in ascending order by their start_offset and cannot be
   // overlapped with each other.
   CompositionUnderlines underlines;
 
   // Selection range in the composition text. It represents the caret position
   // if the range length is zero. Usually it's used for representing the target
   // clause (on Windows). Gtk doesn't have such concept, so background color is
   // usually used instead.
   gfx::Range selection;
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_IME_COMPOSITION_TEXT_H_