Permitting double start/stopping of streams.

It doesn't make too much sense to hard enforce that the user keeps track
of which streams are started and which are not.

BUG=
R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/6899004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5363 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/video/video_send_stream.cc b/video/video_send_stream.cc
index 0ab7039..3f0e593 100644
--- a/video/video_send_stream.cc
+++ b/video/video_send_stream.cc
@@ -259,17 +259,13 @@
 VideoSendStreamInput* VideoSendStream::Input() { return this; }
 
 void VideoSendStream::StartSending() {
-  if (video_engine_base_->StartSend(channel_) != 0)
-    abort();
-  if (video_engine_base_->StartReceive(channel_) != 0)
-    abort();
+  video_engine_base_->StartSend(channel_);
+  video_engine_base_->StartReceive(channel_);
 }
 
 void VideoSendStream::StopSending() {
-  if (video_engine_base_->StopSend(channel_) != 0)
-    abort();
-  if (video_engine_base_->StopReceive(channel_) != 0)
-    abort();
+  video_engine_base_->StopSend(channel_);
+  video_engine_base_->StopReceive(channel_);
 }
 
 bool VideoSendStream::SetCodec(const VideoCodec& codec) {