VCD: Remove the DCHECK in CameraHalDispatcherImpl::RegisterClient

Removes the DCHECK in CameraHalDispatcherImpl::RegisterClient. This is
failing DCHECK because ArcCameraBridge would call RegisterClient on its
own thread directly.

Bug: b/173577612
Test: Build simplechrome
Change-Id: I919a717765aef085b58552de5cf3f9dd167388d7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2546309
Commit-Queue: Jasmine Chen <lnishan@google.com>
Commit-Queue: Wei Lee <wtlee@chromium.org>
Auto-Submit: Jasmine Chen <lnishan@google.com>
Reviewed-by: Wei Lee <wtlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828657}

media/capture/video/chromeos/camera_hal_dispatcher_impl.cc

@@ -232,7 +232,10 @@ void CameraHalDispatcherImpl::RegisterServerWithToken(
 
 void CameraHalDispatcherImpl::RegisterClient(
     mojo::PendingRemote<cros::mojom::CameraHalClient> client) {
-  DCHECK(proxy_task_runner_->BelongsToCurrentThread());
+  // RegisterClient can be called locally by ArcCameraBridge. Unretained
+  // reference is safe here because CameraHalDispatcherImpl owns
+  // |proxy_thread_|.
+
   // TODO(b/170075468): Reject this call once we've migrated all camera clients.
   auto temporary_token = base::UnguessableToken::Create();
   RegisterClientWithToken(std::move(client),
@@ -245,9 +248,6 @@ void CameraHalDispatcherImpl::RegisterClientWithToken(
     cros::mojom::CameraClientType type,
     const base::UnguessableToken& auth_token,
     RegisterClientWithTokenCallback callback) {
-  // RegisterClient can be called locally by ArcCameraBridge. Unretained
-  // reference is safe here because CameraHalDispatcherImpl owns
-  // |proxy_thread_|.
   base::UnguessableToken client_auth_token = auth_token;
   proxy_task_runner_->PostTask(
       FROM_HERE,