in rtp_rtcp module:
  fixed build/namespaces lint errors
  fixed readability/namespace lint errors

BUG=webrtc:5277
R=mflodman,stefan@webrtc.org

Review URL: https://codereview.webrtc.org/1506823002

Cr-Commit-Position: refs/heads/master@{#10978}
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_receiver.cc b/webrtc/modules/rtp_rtcp/source/rtcp_receiver.cc
index b914838..e172139 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_receiver.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_receiver.cc
@@ -23,8 +23,13 @@
 #include "webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.h"
 
 namespace webrtc {
-using namespace RTCPUtility;
-using namespace RTCPHelp;
+using RTCPHelp::RTCPPacketInformation;
+using RTCPHelp::RTCPReceiveInformation;
+using RTCPHelp::RTCPReportBlockInformation;
+using RTCPUtility::kBtVoipMetric;
+using RTCPUtility::RTCPCnameInformation;
+using RTCPUtility::RTCPPacketReportBlockItem;
+using RTCPUtility::RTCPPacketTypes;
 
 // The number of RTCP time intervals needed to trigger a timeout.
 const int kRrTimeoutIntervals = 3;