Uncomment commented-out sequence-checks in call.cc

Two of the three commented-out checks should have been fixed by https://codereview.webrtc.org/2998923002/. The last will be fixed in a separate CL.

BUG=webrtc:8116

Review-Url: https://codereview.webrtc.org/2999253002
Cr-Original-Commit-Position: refs/heads/master@{#19511}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: d1dd2f79e5f290ef0f21f5c050aa0111732a0f71
diff --git a/call/call.cc b/call/call.cc
index f2bf27e..cee0036 100644
--- a/call/call.cc
+++ b/call/call.cc
@@ -590,9 +590,7 @@
 }
 
 PacketReceiver* Call::Receiver() {
-  // TODO(solenberg): Some test cases in EndToEndTest use this from a different
-  // thread. Re-enable once that is fixed.
-  //  RTC_DCHECK_CALLED_SEQUENTIALLY(&configuration_sequence_checker_);
+  RTC_DCHECK_CALLED_SEQUENTIALLY(&configuration_sequence_checker_);
   return this;
 }
 
@@ -1372,10 +1370,7 @@
     const uint8_t* packet,
     size_t length,
     const PacketTime& packet_time) {
-  // TODO(solenberg): Tests call this function on a network thread, libjingle
-  // calls on the worker thread. We should move towards always using a network
-  // thread. Then this check can be enabled.
-  // RTC_DCHECK_CALLED_SEQUENTIALLY(&configuration_sequence_checker_);
+  RTC_DCHECK_CALLED_SEQUENTIALLY(&configuration_sequence_checker_);
   if (RtpHeaderParser::IsRtcp(packet, length))
     return DeliverRtcp(media_type, packet, length);