Add missing (and remove superfluous) 'explicit' from constructors.

remoting/host/json_host_config.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 REMOTING_HOST_JSON_HOST_CONFIG_H_
 #define REMOTING_HOST_JSON_HOST_CONFIG_H_
 
 #include <string>
 
 #include "base/file_path.h"
 #include "remoting/host/in_memory_host_config.h"
 
 namespace base {
 class MessageLoopProxy;
 }  // namespace base
 
 namespace remoting {
 
 // JsonHostConfig implements MutableHostConfig for JSON file.
 class JsonHostConfig : public InMemoryHostConfig {
  public:
-  JsonHostConfig(const FilePath& filename);
+  explicit JsonHostConfig(const FilePath& filename);
   virtual ~JsonHostConfig();
 
   virtual bool Read();
 
   // MutableHostConfig interface.
   virtual bool Save() OVERRIDE;
 
   std::string GetSerializedData();
 
   // Sets the configuration from serialized JSON data. Returns false if the data
   // could not be parsed.
   bool SetSerializedData(const std::string& config);
 
  private:
   FilePath filename_;
 
   DISALLOW_COPY_AND_ASSIGN(JsonHostConfig);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_JSON_HOST_CONFIG_H_