Enable cpplint in pc/

Enable cpplint check in the PRESUBMIT for pc/ and fix all existing
warnings.

Bug: webrtc:5583
Change-Id: If39994692ab6f6f3c83c74f23850f02fdfe810e8
Reviewed-on: https://webrtc-review.googlesource.com/16540
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20482}
diff --git a/pc/rtpsender.h b/pc/rtpsender.h
index 672637f..ce8c657 100644
--- a/pc/rtpsender.h
+++ b/pc/rtpsender.h
@@ -17,6 +17,7 @@
 
 #include <memory>
 #include <string>
+#include <vector>
 
 #include "api/mediastreaminterface.h"
 #include "api/rtpsenderinterface.h"