Make SendStatisticsProxy outlive ViEChannel.

Prevents data race on stats_proxy_ on VideoSendStream destruction.

BUG=
TBR=mflodman@webrtc.org

Review URL: https://codereview.webrtc.org/1409133006 .

Cr-Commit-Position: refs/heads/master@{#10493}
diff --git a/webrtc/video/video_send_stream.cc b/webrtc/video/video_send_stream.cc
index 67e8a9c..a03eacb 100644
--- a/webrtc/video/video_send_stream.cc
+++ b/webrtc/video/video_send_stream.cc
@@ -117,7 +117,8 @@
     const VideoSendStream::Config& config,
     const VideoEncoderConfig& encoder_config,
     const std::map<uint32_t, RtpState>& suspended_ssrcs)
-    : transport_adapter_(config.send_transport),
+    : stats_proxy_(Clock::GetRealTimeClock(), config),
+      transport_adapter_(config.send_transport),
       encoded_frame_proxy_(config.post_encode_callback),
       config_(config),
       suspended_ssrcs_(suspended_ssrcs),
@@ -125,8 +126,7 @@
       call_stats_(call_stats),
       congestion_controller_(congestion_controller),
       encoder_feedback_(new EncoderStateFeedback()),
-      use_config_bitrate_(true),
-      stats_proxy_(Clock::GetRealTimeClock(), config) {
+      use_config_bitrate_(true) {
   LOG(LS_INFO) << "VideoSendStream: " << config_.ToString();
   RTC_DCHECK(!config_.rtp.ssrcs.empty());
 
diff --git a/webrtc/video/video_send_stream.h b/webrtc/video/video_send_stream.h
index 88c1611..36a87e3 100644
--- a/webrtc/video/video_send_stream.h
+++ b/webrtc/video/video_send_stream.h
@@ -72,6 +72,8 @@
  private:
   bool SetSendCodec(VideoCodec video_codec);
   void ConfigureSsrcs();
+
+  SendStatisticsProxy stats_proxy_;
   TransportAdapter transport_adapter_;
   EncodedFrameCallbackAdapter encoded_frame_proxy_;
   const VideoSendStream::Config config_;
@@ -91,8 +93,6 @@
   // start bitrate initially, instead of the one reported by VideoEngine (which
   // defaults to too high).
   bool use_config_bitrate_;
-
-  SendStatisticsProxy stats_proxy_;
 };
 }  // namespace internal
 }  // namespace webrtc