Bug 1536668 - Add more check to RecvGetTextureFactoryIdentifier() r=nical

Add a check similar to LayerTransactionParent::RecvSetAsyncZoom()

Differential Revision: https://phabricator.services.mozilla.com/D30308

--HG--
extra : moz-landing-system : lando

gfx/layers/ipc/LayerTransactionParent.cpp

@@ -1031,7 +1031,7 @@ mozilla::ipc::IPCResult LayerTransactionParent::RecvRecordPaintTimes(
 
 mozilla::ipc::IPCResult LayerTransactionParent::RecvGetTextureFactoryIdentifier(
     TextureFactoryIdentifier* aIdentifier) {
-  if (!mLayerManager) {
+  if (mDestroyed || !mLayerManager || mLayerManager->IsDestroyed()) {
     // Default constructor sets mParentBackend to LAYERS_NONE.
     return IPC_OK();
   }