json_schema_compiler: Use std::vector<char> for binary values.

content/public/browser/speech_recognition_session_preamble.h

 // Copyright 2014 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_PUBLIC_BROWSER_SPEECH_RECOGNITION_SESSION_PREAMBLE_H_
 #define CONTENT_PUBLIC_BROWSER_SPEECH_RECOGNITION_SESSION_PREAMBLE_H_
 
-#include <string>
+#include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 // The preamble is the few seconds of audio before the speech recognition
 // starts. This is used to contain trigger audio used to start a voice
 // query, such as the 'Ok Google' hotword.
 struct CONTENT_EXPORT SpeechRecognitionSessionPreamble
     : public base::RefCounted<SpeechRecognitionSessionPreamble> {
   SpeechRecognitionSessionPreamble();
 
   // Sampling rate (hz) for the preamble data. i.e. 44100, 32000, etc
   int sample_rate;
 
   // Bytes per sample.
   int sample_depth;
 
   // Audio data, in little-endian samples.
-  std::string sample_data;
+  std::vector<char> sample_data;
 
  private:
   friend class base::RefCounted<SpeechRecognitionSessionPreamble>;
   ~SpeechRecognitionSessionPreamble();
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_SPEECH_RECOGNITION_SESSION_PREAMBLE_H_