Enable cpplint and fix cpplint errors in webrtc/api

webrtc/api/statstypes.h

 /*
  *  Copyright 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 // This file contains structures used for retrieving statistics from an ongoing
 // libjingle session.
 
 #ifndef WEBRTC_API_STATSTYPES_H_
 #define WEBRTC_API_STATSTYPES_H_
 
 #include <algorithm>
 #include <list>
 #include <map>
 #include <string>
+#include <vector>
 
 #include "webrtc/base/basictypes.h"
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/refcount.h"
 #include "webrtc/base/scoped_ref_ptr.h"
 #include "webrtc/base/stringencode.h"
 #include "webrtc/base/thread_checker.h"
 
 namespace webrtc {
 
@@ skipping 196 matching lines @@
     bool Equals(const rtc::scoped_refptr<IdBase>& other) const {
       return Equals(*other.get());
     }
 
     virtual std::string ToString() const = 0;
 
    protected:
     // Protected since users of the IdBase type will be using the Id typedef.
     virtual bool Equals(const IdBase& other) const;
 
-    IdBase(StatsType type);  // Only meant for derived classes.
+    explicit IdBase(StatsType type);  // Only meant for derived classes.
     const StatsType type_;
 
     static const char kSeparator = '_';
   };
 
   typedef rtc::scoped_refptr<IdBase> Id;
 
   struct Value {
     enum Type {
       kInt,           // int.
@@ skipping 171 matching lines @@
   StatsReport* Find(const StatsReport::Id& id);
 
  private:
   Container list_;
   rtc::ThreadChecker thread_checker_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_STATSTYPES_H_