Adds the active field to SimulcastStream and VideoCodec structs.

These needed to be added so that changes can be made to downstream
clients to prevent downstream test failures from another CL.
https://webrtc-review.googlesource.com/c/src/+/39883

TBR=solenberg@webrtc.org

Bug: webrtc:8653
Change-Id: I5bbc33080f6fb3a683319ee642f7cb71fe360608
Reviewed-on: https://webrtc-review.googlesource.com/40384
Reviewed-by: Seth Hampson <shampson@webrtc.org>
Commit-Queue: Seth Hampson <shampson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21664}

common_types.cc

@@ -31,6 +31,7 @@ VideoCodec::VideoCodec()
       minBitrate(0),
       targetBitrate(0),
       maxFramerate(0),
+      active(true),
       qpMax(0),
       numberOfSimulcastStreams(0),
       simulcastStream(),

common_types.h

@@ -509,6 +509,7 @@ struct SimulcastStream {
   unsigned int targetBitrate;  // kilobits/sec.
   unsigned int minBitrate;     // kilobits/sec.
   unsigned int qpMax;          // minimum quality
+  bool active;                 // encoded and sent.
 };
 
 struct SpatialLayer {
@@ -540,6 +541,10 @@ class VideoCodec {
 
   uint32_t maxFramerate;
 
+  // This enables/disables encoding and sending when there aren't multiple
+  // simulcast streams,by allocating 0 bitrate if inactive.
+  bool active;
+
   unsigned int qpMax;
   unsigned char numberOfSimulcastStreams;
   SimulcastStream simulcastStream[kMaxSimulcastStreams];