[rtp_rtcp] fixed lint errors in rtp_rtcp module that are not fixed in other CLs

webrtc/modules/rtp_rtcp/source/rtp_receiver_strategy.h

Index: webrtc/modules/rtp_rtcp/source/rtp_receiver_strategy.h
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_receiver_strategy.h b/webrtc/modules/rtp_rtcp/source/rtp_receiver_strategy.h
index 0e0a34a4a43ca329f60cc8a5a89fd4ee6bd1f0c2..0f7ad30e872be3c4251d0c57c4702b83ebd90211 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_receiver_strategy.h
+++ b/webrtc/modules/rtp_rtcp/source/rtp_receiver_strategy.h
@@ -95,7 +95,7 @@ class RTPReceiverStrategy {
   // Note: Implementations may call the callback for other reasons than calls
   // to ParseRtpPacket, for instance if the implementation somehow recovers a
   // packet.
-  RTPReceiverStrategy(RtpData* data_callback);
+  explicit RTPReceiverStrategy(RtpData* data_callback);
 
   rtc::scoped_ptr<CriticalSectionWrapper> crit_sect_;
   PayloadUnion last_payload_;