Use base::string16 for CompositionText.Text instead of converting to utf-8 and back unnecessarily.

chrome/browser/chromeos/input_method/input_method_engine.cc

 // 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.
 
 #include "chrome/browser/chromeos/input_method/input_method_engine.h"
 
 #define XK_MISCELLANY
 #include <X11/keysymdef.h>
 #include <X11/X.h>
 #include <X11/Xlib.h>
@@ skipping 126 matching lines @@
     *error = kErrorNotActive;
     return false;
   }
   if (context_id != context_id_ || context_id_ == -1) {
     *error = kErrorWrongContext;
     return false;
   }
 
   composition_cursor_ = cursor;
   composition_text_.reset(new CompositionText());
-  composition_text_->set_text(text);
+  composition_text_->set_text(base::UTF8ToUTF16(text));
 
   composition_text_->set_selection_start(selection_start);
   composition_text_->set_selection_end(selection_end);
 
   // TODO: Add support for displaying selected text in the composition string.
   for (std::vector<SegmentInfo>::const_iterator segment = segments.begin();
        segment != segments.end(); ++segment) {
     CompositionText::UnderlineAttribute underline;
 
     switch (segment->style) {
@@ skipping 460 matching lines @@
           // TODO(nona): Implement it.
           break;
       }
     }
   }
 
   // TODO(nona): Support item.children.
 }
 
 }  // namespace chromeos