Move RTCP histograms from vie_channel to video channel stats proxies.

webrtc/video/send_statistics_proxy_unittest.cc

Index: webrtc/video/send_statistics_proxy_unittest.cc
diff --git a/webrtc/video/send_statistics_proxy_unittest.cc b/webrtc/video/send_statistics_proxy_unittest.cc
index cf54190d1397c438c0df40dcfc7cedc81d81b8dd..d05983106a0d6815787e6334959df72189399e61 100644
--- a/webrtc/video/send_statistics_proxy_unittest.cc
+++ b/webrtc/video/send_statistics_proxy_unittest.cc
@@ -86,8 +86,8 @@ class SendStatisticsProxyTest : public ::testing::Test {
     }
   }

[pbos-webrtc, 2016/02/23 15:15:26]

Can you add a test for the -= start_stats_ mechanism?

[sprang, 2016/02/23 16:42:10]

Done.
Also fixed the bug it caught :/

 
-  rtc::scoped_ptr<SendStatisticsProxy> statistics_proxy_;
   SimulatedClock fake_clock_;
+  rtc::scoped_ptr<SendStatisticsProxy> statistics_proxy_;
   VideoSendStream::Config config_;
   int avg_delay_ms_;
   int max_delay_ms_;