Convert JsonWriter::Write to taking a const ref for the in-param

chrome/browser/extensions/api/media_galleries/media_galleries_apitest.cc

 // 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.
 
 #include "base/auto_reset.h"
 #include "base/callback.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/json/json_writer.h"
 #include "base/numerics/safe_conversions.h"
@@ skipping 146 matching lines @@
         GetCommonDataDir().AppendASCII("common_injected.js"));
     base::FilePath inject_js_path(
         temp_dir.path().AppendASCII(extension_name)
                        .AppendASCII("common_injected.js"));
     if (!base::CopyFile(common_js_path, inject_js_path))
       return false;
 
     const char* custom_arg = NULL;
     std::string json_string;
     if (!custom_arg_value.empty()) {
-      base::JSONWriter::Write(&custom_arg_value, &json_string);
+      base::JSONWriter::Write(custom_arg_value, &json_string);
       custom_arg = json_string.c_str();
     }
 
     base::AutoReset<base::FilePath> reset(&test_data_dir_, temp_dir.path());
     bool result = RunPlatformAppTestWithArg(extension_name, custom_arg);
     content::RunAllPendingInMessageLoop();  // avoid race on exit in registry.
     return result;
   }
 
   void AttachFakeDevice() {
@@ skipping 493 matching lines @@
 
   base::ListValue custom_args;
 #if defined(USE_PROPRIETARY_CODECS)
   custom_args.AppendBoolean(true);
 #else
   custom_args.AppendBoolean(false);
 #endif
   ASSERT_TRUE(RunMediaGalleriesTestWithArg("media_metadata", custom_args))
       << message_;
 }