Let ViEEncoder handle resolution changes.

webrtc/video_send_stream.h

Index: webrtc/video_send_stream.h
diff --git a/webrtc/video_send_stream.h b/webrtc/video_send_stream.h
index 2948d46874245962bf3488b2090952abc4f9f2d6..d33a3cdd86657b812d6e515db3f5cbb5b3cff24b 100644
--- a/webrtc/video_send_stream.h
+++ b/webrtc/video_send_stream.h
@@ -14,6 +14,7 @@
 #include <map>
 #include <string>
 #include <vector>
+#include <utility>
 
 #include "webrtc/common_types.h"
 #include "webrtc/common_video/include/frame_callback.h"
@@ -53,8 +54,14 @@ class VideoSendStream {
     int encode_frame_rate = 0;
     int avg_encode_time_ms = 0;
     int encode_usage_percent = 0;
+    // Bitrate the encoder is currently configured to use due to bandwidth
+    // limitations.
     int target_media_bitrate_bps = 0;
+    // Bitrate the encoder is actually producing.
     int media_bitrate_bps = 0;
+    // Media bitrate this VideoSendStream is configured to prefer if there are
+    // no bandwidth limitations.
+    int preffered_media_bitrate_bps = 0;
     bool suspended = false;
     bool bw_limited_resolution = false;
     std::map<uint32_t, StreamStats> substreams;