Add some sanity CHECKs to webrtc::Call.

These checks would help catching double-deletes, forgetting to destroy
streams and also catch if VideoEngine has held on to any stale
references.

BUG=1788
R=stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/42929004

Cr-Commit-Position: refs/heads/master@{#8866}

webrtc/video/call.cc

diff --git a/webrtc/video/call.cc b/webrtc/video/call.cc
index c455ba8..d9dc334 100644
--- a/webrtc/video/call.cc
+++ b/webrtc/video/call.cc
@@ -229,6 +229,8 @@
 }
 
 Call::~Call() {
+  CHECK_EQ(0u, send_ssrcs_.size());
+  CHECK_EQ(0u, receive_ssrcs_.size());
   base_->DeleteChannel(base_channel_id_);
 
   render_->DeRegisterVideoRenderModule(*external_render_.get());
@@ -238,7 +240,7 @@
   codec_->Release();
   render_->Release();
   rtp_rtcp_->Release();
-  webrtc::VideoEngine::Delete(video_engine_);
+  CHECK(webrtc::VideoEngine::Delete(video_engine_));
 }
 
 PacketReceiver* Call::Receiver() { return this; }
@@ -288,6 +290,7 @@
       }
     }
   }
+  CHECK(send_stream_impl != nullptr);
 
   VideoSendStream::RtpStateMap rtp_state = send_stream_impl->GetRtpStates();
 
@@ -297,7 +300,6 @@
     suspended_send_ssrcs_[it->first] = it->second;
   }
 
-  DCHECK(send_stream_impl != nullptr);
   delete send_stream_impl;
 }
 
@@ -352,8 +354,7 @@
       }
     }
   }
-
-  DCHECK(receive_stream_impl != nullptr);
+  CHECK(receive_stream_impl != nullptr);
   delete receive_stream_impl;
 }