Bug 1377324 - Don't compute prepared data multiple times for ContainerLayers that are duplicated. r=miko

gfx/layers/composite/ContainerLayerComposite.cpp

@@ -185,6 +185,12 @@ ContainerPrepare(ContainerT* aContainer,
                  LayerManagerComposite* aManager,
                  const RenderTargetIntRect& aClipRect)
 {
+  // We can end up calling prepare multiple times if we duplicated
+  // layers due to preserve-3d plane splitting. The results
+  // should be identical, so we only need to do it once.
+  if (aContainer->mPrepared) {
+    return;
+  }
   aContainer->mPrepared = MakeUnique<PreparedData>();
   aContainer->mPrepared->mNeedsSurfaceCopy = false;
 
@@ -687,6 +693,10 @@ void
 ContainerLayerComposite::Cleanup()
 {
   mPrepared = nullptr;
+
+  for (Layer* l = GetFirstChild(); l; l = l->GetNextSibling()) {
+    static_cast<LayerComposite*>(l->AsHostLayer())->Cleanup();
+  }
 }
 
 void
@@ -754,6 +764,16 @@ RefLayerComposite::Prepare(const RenderTargetIntRect& aClipRect)
   ContainerPrepare(this, mCompositeManager, aClipRect);
 }
 
+void
+RefLayerComposite::Cleanup()
+{
+  mPrepared = nullptr;
+
+  for (Layer* l = GetFirstChild(); l; l = l->GetNextSibling()) {
+    static_cast<LayerComposite*>(l->AsHostLayer())->Cleanup();
+  }
+}
+
 void
 RefLayerComposite::CleanupResources()
 {

gfx/layers/composite/ContainerLayerComposite.h

@@ -183,6 +183,8 @@ public:
     DefaultComputeEffectiveTransforms(aTransformToSurface);
   }
 
+  virtual void Cleanup() override;
+
   virtual void CleanupResources() override;
 
   virtual HostLayer* AsHostLayer() override { return this; }