Bug 1622360 - Drop RenderRootStateManager::mRenderRoot. r=jrmuizel

Depends on D74944

Differential Revision: https://phabricator.services.mozilla.com/D74945

gfx/layers/wr/RenderRootStateManager.cpp

@@ -36,7 +36,6 @@ RenderRootStateManager::GetWebRenderUserDataTable() {
 
 wr::IpcResourceUpdateQueue& RenderRootStateManager::AsyncResourceUpdates() {
   MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(XRE_IsParentProcess() || mRenderRoot == wr::RenderRoot::Default);
 
   if (!mAsyncResourceUpdates) {
     mAsyncResourceUpdates.emplace(WrBridge());

gfx/layers/wr/RenderRootStateManager.h

@@ -27,12 +27,10 @@ class RenderRootStateManager {
 
   RenderRootStateManager()
       : mLayerManager(nullptr),
-        mRenderRoot(wr::RenderRoot::Default),
         mDestroyed(false) {}
 
   void Destroy();
   bool IsDestroyed() { return mDestroyed; }
-  wr::RenderRoot GetRenderRoot() { return mRenderRoot; }
   wr::IpcResourceUpdateQueue& AsyncResourceUpdates();
   WebRenderBridgeChild* WrBridge() const;
   WebRenderCommandBuilder& CommandBuilder();
@@ -93,7 +91,6 @@ class RenderRootStateManager {
   // the compositor to discard information for.
   nsTArray<uint64_t> mDiscardedCompositorAnimationsIds;
 
-  wr::RenderRoot mRenderRoot;
   bool mDestroyed;
 
   friend class WebRenderLayerManager;

gfx/layers/wr/WebRenderLayerManager.cpp

@@ -42,7 +42,6 @@ WebRenderLayerManager::WebRenderLayerManager(nsIWidget* aWidget)
       mWebRenderCommandBuilder(this),
       mLastDisplayListSize(0) {
   MOZ_COUNT_CTOR(WebRenderLayerManager);
-  mStateManager.mRenderRoot = wr::RenderRoot::Default;
   mStateManager.mLayerManager = this;
 
   if (XRE_IsContentProcess() &&