media: Only unregister a CDM when it has been registered.

media/mojo/services/mojo_cdm_service.cc

Index: media/mojo/services/mojo_cdm_service.cc
diff --git a/media/mojo/services/mojo_cdm_service.cc b/media/mojo/services/mojo_cdm_service.cc
index 31781b11e5fc5ec183dcd62c50f86ee04c0d3d5f..b2529bf22a67561c366bda31ee1d7b8e58d87c18 100644
--- a/media/mojo/services/mojo_cdm_service.cc
+++ b/media/mojo/services/mojo_cdm_service.cc
@@ -93,9 +93,12 @@ MojoCdmService::MojoCdmService(
 }
 
 MojoCdmService::~MojoCdmService() {
+  if (cdm_id_ == CdmContext::kInvalidCdmId)
+    return;
+
   g_cdm_manager.Get().UnregisterCdm(cdm_id_);
 
-  if (cdm_id_ != CdmContext::kInvalidCdmId && context_)
+  if (context_)
     context_->UnregisterCdm(cdm_id_);
 }