Enable cpplint in media/

Bug: webrtc:5584
Change-Id: I2fd1395d35596d9002e19cc90fcda3a5d4cde9e7
Reviewed-on: https://webrtc-review.googlesource.com/16564
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20504}
diff --git a/media/base/mediachannel.h b/media/base/mediachannel.h
index 06766a8..1fed49c 100644
--- a/media/base/mediachannel.h
+++ b/media/base/mediachannel.h
@@ -11,6 +11,7 @@
 #ifndef MEDIA_BASE_MEDIACHANNEL_H_
 #define MEDIA_BASE_MEDIACHANNEL_H_
 
+#include <map>
 #include <memory>
 #include <string>
 #include <vector>
@@ -1223,7 +1224,7 @@
   };
 
   DataMediaChannel() {}
-  DataMediaChannel(const MediaConfig& config) : MediaChannel(config) {}
+  explicit DataMediaChannel(const MediaConfig& config) : MediaChannel(config) {}
   virtual ~DataMediaChannel() {}
 
   virtual bool SetSendParameters(const DataSendParameters& params) = 0;