Enable cpplint and fix cpplint errors in webrtc/api

webrtc/api/umametrics.h

 /*
  *  Copyright 2014 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.
  */
 
@@ skipping 95 matching lines @@
   // public IP addresses.
   kIceCandidatePairHostPrivateHostPrivate,
   kIceCandidatePairHostPrivateHostPublic,
   kIceCandidatePairHostPublicHostPrivate,
   kIceCandidatePairHostPublicHostPublic,
   kIceCandidatePairMax
 };
 
 class MetricsObserverInterface : public rtc::RefCountInterface {
  public:
-
   // |type| is the type of the enum counter to be incremented. |counter|
   // is the particular counter in that type. |counter_max| is the next sequence
   // number after the highest counter.
   virtual void IncrementEnumCounter(PeerConnectionEnumCounterType type,
                                     int counter,
                                     int counter_max) {}
 
   // This is used to handle sparse counters like SSL cipher suites.
   // TODO(guoweis): Remove the implementation once the dependency's interface
   // definition is updated.
   virtual void IncrementSparseEnumCounter(PeerConnectionEnumCounterType type,
                                           int counter) {
     IncrementEnumCounter(type, counter, 0 /* Ignored */);
   }
 
   virtual void AddHistogramSample(PeerConnectionMetricsName type,
                                   int value) = 0;
 
  protected:
   virtual ~MetricsObserverInterface() {}
 };
 
 typedef MetricsObserverInterface UMAObserver;
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_UMAMETRICS_H_