Enable cpplint and fix cpplint errors in webrtc/api

webrtc/api/peerconnectioninterface.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.
  */
 
@@ skipping 270 matching lines @@
   // need getters and setters at least for fields which applications
   // are interested in.
   struct RTCConfiguration {
     // This struct is subject to reorganization, both for naming
     // consistency, and to group settings to match where they are used
     // in the implementation. To do that, we need getter and setter
     // methods for all settings which are of interest to applications,
     // Chrome in particular.
 
     RTCConfiguration() = default;
-    RTCConfiguration(RTCConfigurationType type) {
+    explicit RTCConfiguration(RTCConfigurationType type) {
       if (type == RTCConfigurationType::kAggressive) {
         // These parameters are also defined in Java and IOS configurations,
         // so their values may be overwritten by the Java or IOS configuration.
         bundle_policy = kBundlePolicyMaxBundle;
         rtcp_mux_policy = kRtcpMuxPolicyRequire;
         ice_connection_receiving_timeout =
             kAggressiveIceConnectionReceivingTimeout;
 
         // These parameters are not defined in Java or IOS configuration,
         // so their values will not be overwritten.
@@ skipping 360 matching lines @@
   virtual void OnAddStream(MediaStreamInterface* stream) {}
 
   // Triggered when a remote peer close a stream.
   virtual void OnRemoveStream(rtc::scoped_refptr<MediaStreamInterface> stream) {
   }
   // Deprecated; please use the version that uses a scoped_refptr.
   virtual void OnRemoveStream(MediaStreamInterface* stream) {}
 
   // Triggered when a remote peer opens a data channel.
   virtual void OnDataChannel(
-      rtc::scoped_refptr<DataChannelInterface> data_channel){};
+      rtc::scoped_refptr<DataChannelInterface> data_channel) {}
   // Deprecated; please use the version that uses a scoped_refptr.
   virtual void OnDataChannel(DataChannelInterface* data_channel) {}
 
   // Triggered when renegotiation is needed. For example, an ICE restart
   // has begun.
   virtual void OnRenegotiationNeeded() = 0;
 
   // Called any time the IceConnectionState changes.
   virtual void OnIceConnectionChange(
       PeerConnectionInterface::IceConnectionState new_state) = 0;
@@ skipping 257 matching lines @@
     cricket::WebRtcVideoEncoderFactory* encoder_factory,
     cricket::WebRtcVideoDecoderFactory* decoder_factory) {
   return CreatePeerConnectionFactory(
       worker_and_network_thread, worker_and_network_thread, signaling_thread,
       default_adm, encoder_factory, decoder_factory);
 }
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_PEERCONNECTIONINTERFACE_H_