--- a/gfx/layers/ipc/CompositorBridgeParent.cpp
+++ b/gfx/layers/ipc/CompositorBridgeParent.cpp
@@ -1727,48 +1727,61 @@ CompositorBridgeParent::RecvMapAndNotify
   return IPC_OK();
 }
 
 mozilla::ipc::IPCResult
 CompositorBridgeParent::RecvAdoptChild(const LayersId& child)
 {
   RefPtr<APZUpdater> oldApzUpdater;
   APZCTreeManagerParent* parent;
-  {
+  bool scheduleComposition = false;
+  RefPtr<CrossProcessCompositorBridgeParent> cpcp;
+  RefPtr<WebRenderBridgeParent> childWrBridge;
+
+  { // scope lock
     MonitorAutoLock lock(*sIndirectLayerTreesLock);
     if (sIndirectLayerTrees[child].mParent) {
       // We currently don't support adopting children from one compositor to
       // another if the two compositors don't have the same options.
       MOZ_ASSERT(sIndirectLayerTrees[child].mParent->mOptions == mOptions);
       oldApzUpdater = sIndirectLayerTrees[child].mParent->mApzUpdater;
     }
     NotifyChildCreated(child);
     if (sIndirectLayerTrees[child].mLayerTree) {
       sIndirectLayerTrees[child].mLayerTree->SetLayerManager(mLayerManager, GetAnimationStorage());
       // Trigger composition to handle a case that mLayerTree was not composited yet
       // by previous CompositorBridgeParent, since nsRefreshDriver might wait composition complete.
-      ScheduleComposition();
+      scheduleComposition = true;
     }
-    if (mWrBridge && sIndirectLayerTrees[child].mWrBridge) {
-      RefPtr<wr::WebRenderAPI> api = mWrBridge->GetWebRenderAPI();
-      api = api->Clone();
-      sIndirectLayerTrees[child].mWrBridge->UpdateWebRender(mWrBridge->CompositorScheduler(),
-                                                            api,
-                                                            mWrBridge->AsyncImageManager(),
-                                                            GetAnimationStorage());
-      // Pretend we composited, since parent CompositorBridgeParent was replaced.
-      CrossProcessCompositorBridgeParent* cpcp = sIndirectLayerTrees[child].mCrossProcessParent;
-      if (cpcp) {
-        TimeStamp now = TimeStamp::Now();
-        cpcp->DidCompositeLocked(child, now, now);
-      }
+    if (mWrBridge) {
+      childWrBridge = sIndirectLayerTrees[child].mWrBridge;
+      cpcp = sIndirectLayerTrees[child].mCrossProcessParent;
     }
     parent = sIndirectLayerTrees[child].mApzcTreeManagerParent;
   }
 
+  if (scheduleComposition) {
+    ScheduleComposition();
+  }
+
+  if (childWrBridge) {
+    MOZ_ASSERT(mWrBridge);
+    RefPtr<wr::WebRenderAPI> api = mWrBridge->GetWebRenderAPI();
+    api = api->Clone();
+    childWrBridge->UpdateWebRender(mWrBridge->CompositorScheduler(),
+                                   api,
+                                   mWrBridge->AsyncImageManager(),
+                                   GetAnimationStorage());
+    // Pretend we composited, since parent CompositorBridgeParent was replaced.
+    if (cpcp) {
+      TimeStamp now = TimeStamp::Now();
+      cpcp->DidComposite(child, now, now);
+    }
+  }
+
   if (oldApzUpdater) {
     // We don't support moving a child from an APZ-enabled compositor to a
     // APZ-disabled compositor. The mOptions assertion above should already
     // ensure this, since APZ-ness is one of the things in mOptions. Note
     // however it is possible for mApzUpdater to be non-null here with
     // oldApzUpdater null, because the child may not have been previously
     // composited.
     MOZ_ASSERT(mApzUpdater);