Comment out DCHECK in dtor of VCMDecodedFrameCallback.
Looking into the downstream issue now.

NoTry: true
Tbr: ossu@webrtc.org
Bug: webrtc:7361, webrtc:8907, chromium:695438
Change-Id: Ib52b86cf26401c490b415b151916ec35f0716345
Reviewed-on: https://webrtc-review.googlesource.com/56042
Reviewed-by: Tommi <tommi@webrtc.org>
Commit-Queue: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22122}
diff --git a/modules/video_coding/generic_decoder.cc b/modules/video_coding/generic_decoder.cc
index fe68998..5d22ffa 100644
--- a/modules/video_coding/generic_decoder.cc
+++ b/modules/video_coding/generic_decoder.cc
@@ -34,7 +34,8 @@
 }
 
 VCMDecodedFrameCallback::~VCMDecodedFrameCallback() {
-  RTC_DCHECK(construction_thread_.CalledOnValidThread());
+  // TODO(tommi): Re-enable this DCHECK once downstream issues have been fixed.
+  // RTC_DCHECK(construction_thread_.CalledOnValidThread());
 }
 
 void VCMDecodedFrameCallback::SetUserReceiveCallback(