Cleanup: Pass std::string as const reference from content/

content/browser/speech/speech_recognizer_impl_android.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 CONTENT_BROWSER_SPEECH_SPEECH_RECOGNIZER_IMPL_ANDROID_H_
 #define CONTENT_BROWSER_SPEECH_SPEECH_RECOGNIZER_IMPL_ANDROID_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
@@ skipping 31 matching lines @@
 
   static bool RegisterSpeechRecognizer(JNIEnv* env);
 
  private:
   enum State {
     STATE_IDLE = 0,
     STATE_CAPTURING_AUDIO,
     STATE_AWAITING_FINAL_RESULT
   };
 
-  void StartRecognitionOnUIThread(
-      std::string language, bool continuous, bool interim_results);
+  void StartRecognitionOnUIThread(const std::string& language,
+                                  bool continuous,
+                                  bool interim_results);
   void OnRecognitionResultsOnIOThread(SpeechRecognitionResults const &results);
 
   ~SpeechRecognizerImplAndroid() override;
 
   base::android::ScopedJavaGlobalRef<jobject> j_recognition_;
   State state_;
 
   DISALLOW_COPY_AND_ASSIGN(SpeechRecognizerImplAndroid);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SPEECH_SPEECH_RECOGNIZER_IMPL_ANDROID_H_