--- a/gfx/layers/wr/WebRenderBridgeParent.cpp
+++ b/gfx/layers/wr/WebRenderBridgeParent.cpp
@@ -178,17 +178,17 @@ WebRenderBridgeParent::WebRenderBridgePa
   , mPaused(false)
   , mDestroyed(false)
   , mForceRendering(false)
   , mReceivedDisplayList(false)
 {
   MOZ_ASSERT(mAsyncImageManager);
   MOZ_ASSERT(mAnimStorage);
   mAsyncImageManager->AddPipeline(mPipelineId);
-  if (mWidget) {
+  if (IsRootWebRenderBridgeParent()) {
     MOZ_ASSERT(!mCompositorScheduler);
     mCompositorScheduler = new CompositorVsyncScheduler(this, mWidget);
   }
 }
 
 WebRenderBridgeParent::WebRenderBridgeParent(const wr::PipelineId& aPipelineId)
   : mCompositorBridge(nullptr)
   , mPipelineId(aPipelineId)
@@ -496,24 +496,30 @@ WebRenderBridgeParent::RemoveEpochDataPr
       } else {
         NS_ERROR("Tried to delete invalid animation");
       }
     }
     mCompositorAnimationsToDelete.pop();
   }
 }
 
+bool
+WebRenderBridgeParent::IsRootWebRenderBridgeParent() const
+{
+  return !!mWidget;
+}
+
 CompositorBridgeParent*
 WebRenderBridgeParent::GetRootCompositorBridgeParent() const
 {
   if (!mCompositorBridge) {
     return nullptr;
   }
 
-  if (mWidget) {
+  if (IsRootWebRenderBridgeParent()) {
     // This WebRenderBridgeParent is attached to the root
     // CompositorBridgeParent.
     return static_cast<CompositorBridgeParent*>(mCompositorBridge);
   }
 
   // Otherwise, this WebRenderBridgeParent is attached to a
   // CrossProcessCompositorBridgeParent so we have an extra level of
   // indirection to unravel.
@@ -653,17 +659,17 @@ WebRenderBridgeParent::RecvSetDisplayLis
   UpdateAPZScrollData(wrEpoch, std::move(const_cast<WebRenderScrollData&>(aScrollData)));
 
   wr::Vec<uint8_t> dlData(std::move(dl));
 
   // If id namespaces do not match, it means the command is obsolete, probably
   // because the tab just moved to a new window.
   // In that case do not send the commands to webrender.
   if (mIdNamespace == aIdNamespace) {
-    if (mWidget) {
+    if (IsRootWebRenderBridgeParent()) {
       LayoutDeviceIntSize widgetSize = mWidget->GetClientSize();
       LayoutDeviceIntRect docRect(LayoutDeviceIntPoint(), widgetSize);
       txn.SetWindowParameters(widgetSize, docRect);
     }
     gfx::Color clearColor(0.f, 0.f, 0.f, 0.f);
     txn.SetDisplayList(clearColor, wrEpoch, LayerSize(aSize.width, aSize.height),
                        mPipelineId, aContentSize,
                        dlDesc, dlData);
@@ -889,17 +895,17 @@ WebRenderBridgeParent::FlushSceneBuilds(
     ScheduleGenerateFrame();
   }
 }
 
 void
 WebRenderBridgeParent::FlushFrameGeneration()
 {
   MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
-  MOZ_ASSERT(mWidget); // This function is only useful on the root WRBP
+  MOZ_ASSERT(IsRootWebRenderBridgeParent()); // This function is only useful on the root WRBP
 
   // This forces a new GenerateFrame transaction to be sent to the render
   // backend thread, if one is pending. This doesn't block on any other threads.
   mForceRendering = true;
   mCompositorScheduler->FlushPendingComposite();
   mForceRendering = false;
 }
 
@@ -924,17 +930,17 @@ WebRenderBridgeParent::RecvGetSnapshot(P
   }
   MOZ_ASSERT(!mPaused);
 
   // This function should only get called in the root WRBP. If this function
   // gets called in a non-root WRBP, we will set mForceRendering in this WRBP
   // but it will have no effect because CompositeToTarget (which reads the
   // flag) only gets invoked in the root WRBP. So we assert that this is the
   // root WRBP (i.e. has a non-null mWidget) to catch violations of this rule.
-  MOZ_ASSERT(mWidget);
+  MOZ_ASSERT(IsRootWebRenderBridgeParent());
 
   RefPtr<TextureHost> texture = TextureHost::AsTextureHost(aTexture);
   if (!texture) {
     // We kill the content process rather than have it continue with an invalid
     // snapshot, that may be too harsh and we could decide to return some sort
     // of error to the child process and let it deal with it...
     return IPC_FAIL_NO_REASON(this);
   }
@@ -1119,17 +1125,17 @@ WebRenderBridgeParent::RecvClearCachedRe
 
 void
 WebRenderBridgeParent::UpdateWebRender(CompositorVsyncScheduler* aScheduler,
                                        wr::WebRenderAPI* aApi,
                                        AsyncImagePipelineManager* aImageMgr,
                                        CompositorAnimationStorage* aAnimStorage,
                                        const TextureFactoryIdentifier& aTextureFactoryIdentifier)
 {
-  MOZ_ASSERT(!mWidget);
+  MOZ_ASSERT(!IsRootWebRenderBridgeParent());
   MOZ_ASSERT(aScheduler);
   MOZ_ASSERT(aApi);
   MOZ_ASSERT(aImageMgr);
   MOZ_ASSERT(aAnimStorage);
 
   if (mDestroyed) {
     return;
   }
@@ -1373,17 +1379,17 @@ WebRenderBridgeParent::SampleAnimations(
 
   return isAnimating;
 }
 
 void
 WebRenderBridgeParent::CompositeToTarget(gfx::DrawTarget* aTarget, const gfx::IntRect* aRect)
 {
   // This function should only get called in the root WRBP
-  MOZ_ASSERT(mWidget);
+  MOZ_ASSERT(IsRootWebRenderBridgeParent());
 
   // The two arguments are part of the CompositorVsyncSchedulerOwner API but in
   // this implementation they should never be non-null.
   MOZ_ASSERT(aTarget == nullptr);
   MOZ_ASSERT(aRect == nullptr);
 
   AUTO_PROFILER_TRACING("Paint", "CompositeToTraget");
   if (mPaused || !mReceivedDisplayList) {
@@ -1547,32 +1553,32 @@ WebRenderBridgeParent::FlushRenderingAsy
   }
 
   mCompositorScheduler->FlushPendingComposite();
 }
 
 void
 WebRenderBridgeParent::Pause()
 {
-  MOZ_ASSERT(mWidget);
+  MOZ_ASSERT(IsRootWebRenderBridgeParent());
 #ifdef MOZ_WIDGET_ANDROID
-  if (!mWidget || mDestroyed) {
+  if (!IsRootWebRenderBridgeParent() || mDestroyed) {
     return;
   }
   mApi->Pause();
 #endif
   mPaused = true;
 }
 
 bool
 WebRenderBridgeParent::Resume()
 {
-  MOZ_ASSERT(mWidget);
+  MOZ_ASSERT(IsRootWebRenderBridgeParent());
 #ifdef MOZ_WIDGET_ANDROID
-  if (!mWidget || mDestroyed) {
+  if (!IsRootWebRenderBridgeParent() || mDestroyed) {
     return false;
   }
 
   if (!mApi->Resume()) {
     return false;
   }
 #endif
   mPaused = false;
@@ -1618,17 +1624,17 @@ WebRenderBridgeParent::ClearResources()
   mApi->SendTransaction(txn);
 
   for (std::unordered_set<uint64_t>::iterator iter = mActiveAnimations.begin(); iter != mActiveAnimations.end(); iter++) {
     mAnimStorage->ClearById(*iter);
   }
   mActiveAnimations.clear();
   std::queue<CompositorAnimationIdsForEpoch>().swap(mCompositorAnimationsToDelete); // clear queue
 
-  if (mWidget) {
+  if (IsRootWebRenderBridgeParent()) {
     mCompositorScheduler->Destroy();
   }
 
   // Before tearing down mApi we should make sure the above transaction has been
   // flushed back to the render backend thread. Otherwise the cleanup messages
   // that the WebRenderAPI destructor triggers can race ahead of the transaction
   // (because it goes directly to the RB thread, bypassing the scene builder
   // thread) and clear caches etc. that are still in use.
@@ -1734,17 +1740,17 @@ WebRenderBridgeParent::GetNextWrEpoch()
   MOZ_RELEASE_ASSERT(mWrEpoch.mHandle != UINT32_MAX);
   mWrEpoch.mHandle++;
   return mWrEpoch;
 }
 
 void
 WebRenderBridgeParent::ExtractImageCompositeNotifications(nsTArray<ImageCompositeNotificationInfo>* aNotifications)
 {
-  MOZ_ASSERT(mWidget);
+  MOZ_ASSERT(IsRootWebRenderBridgeParent());
   if (mDestroyed) {
     return;
   }
   mAsyncImageManager->FlushImageNotifications(aNotifications);
 }
 
 } // namespace layers
 } // namespace mozilla

--- a/gfx/layers/wr/WebRenderBridgeParent.h
+++ b/gfx/layers/wr/WebRenderBridgeParent.h
@@ -225,16 +225,18 @@ private:
   mozilla::ipc::IPCResult HandleShutdown();
 
   // Returns true if there is any animation (including animations in delay
   // phase).
   bool AdvanceAnimations();
   bool SampleAnimations(nsTArray<wr::WrOpacityProperty>& aOpacityArray,
                         nsTArray<wr::WrTransformProperty>& aTransformArray);
 
+  bool IsRootWebRenderBridgeParent() const;
+
   CompositorBridgeParent* GetRootCompositorBridgeParent() const;
 
   RefPtr<WebRenderBridgeParent> GetRootWebRenderBridgeParent() const;
 
   // Tell APZ what the subsequent sampling's timestamp should be.
   void SetAPZSampleTime();
 
   wr::Epoch GetNextWrEpoch();