Reduce taking locks in RTPSenderVideo::SendVideo

webrtc/modules/rtp_rtcp/source/rtp_sender_video.h

Index: webrtc/modules/rtp_rtcp/source/rtp_sender_video.h
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_sender_video.h b/webrtc/modules/rtp_rtcp/source/rtp_sender_video.h
index 248610441353296df430dddd842a573bca0a5db4..f8c5b7fe670791d72058840dba4fe0fbd60d50bc 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_sender_video.h
+++ b/webrtc/modules/rtp_rtcp/source/rtp_sender_video.h
@@ -42,7 +42,10 @@ class RTPSenderVideo {
 
   virtual RtpVideoCodecTypes VideoCodecType() const;
 
-  size_t FecPacketOverhead() const;
+  size_t FecPacketOverhead() const {
+    rtc::CritScope cs(&crit_);
+    return CalculateFecPacketOverhead();
+  }
 
   static RtpUtility::Payload* CreateVideoPayload(
       const char payload_name[RTP_PAYLOAD_NAME_SIZE],
@@ -74,6 +77,8 @@ class RTPSenderVideo {
   void SetSelectiveRetransmissions(uint8_t settings);
 
  private:
+  size_t CalculateFecPacketOverhead() const EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
   void SendVideoPacket(std::unique_ptr<RtpPacketToSend> packet,
                        StorageType storage);