Revert "Re-land deferred compositing updates with fixed assumptions"

Source/core/rendering/RenderLayerCompositor.h

Index: Source/core/rendering/RenderLayerCompositor.h
diff --git a/Source/core/rendering/RenderLayerCompositor.h b/Source/core/rendering/RenderLayerCompositor.h
index 7807a6b9d768270787f4db6bda1e889c8c024300..c053c065609121da5c92291932848d207390dd1e 100644
--- a/Source/core/rendering/RenderLayerCompositor.h
+++ b/Source/core/rendering/RenderLayerCompositor.h
@@ -47,8 +47,7 @@ enum CompositingUpdateType {
     CompositingUpdateAfterStyleChange,
     CompositingUpdateAfterLayout,
     CompositingUpdateOnScroll,
-    CompositingUpdateOnCompositedScroll,
-    CompositingUpdateFinishAllDeferredWork
+    CompositingUpdateOnCompositedScroll
 };
 
 // RenderLayerCompositor manages the hierarchy of
@@ -93,9 +92,7 @@ public:
     void updateCompositingRequirementsState();
     void setNeedsUpdateCompositingRequirementsState() { m_needsUpdateCompositingRequirementsState = true; }
 
-    // Main entry point for a full update. As needed, this function will compute compositing requirements,
-    // rebuild the composited layer tree, and/or update all the properties assocaited with each layer of the
-    // composited layer tree.
+    // Rebuild the tree of compositing layers
     void updateCompositingLayers(CompositingUpdateType, RenderLayer* updateRoot = 0);
 
     // Update the compositing state of the given layer. Returns true if that state changed.
@@ -198,7 +195,7 @@ public:
     void resetTrackedRepaintRects();
     void setTracksRepaints(bool);
 
-    void setNeedsToRecomputeCompositingRequirements() { m_needsToRecomputeCompositingRequirements = true; }
+    void setShouldReevaluateCompositingAfterLayout() { m_reevaluateCompositingAfterLayout = true; }
 
     // Returns all reasons (direct, indirectly due to subtree, and indirectly due to overlap) that a layer should be composited.
     CompositingReasons reasonsForCompositing(const RenderLayer*) const;
@@ -236,10 +233,6 @@ private:
     void addToOverlapMap(OverlapMap&, RenderLayer*, IntRect& layerBounds, bool& boundsComputed);
     void addToOverlapMapRecursive(OverlapMap&, RenderLayer*, RenderLayer* ancestorLayer = 0);
 
-    // Forces an update for all frames of frame tree recursively. Used only when the mainFrame compositor is ready to
-    // finish all deferred work.
-    static void finishCompositingUpdateForFrameTree(Frame*);
-
     // Returns true if any layer's compositing changed
     void computeCompositingRequirements(RenderLayer* ancestorLayer, RenderLayer*, OverlapMap*, struct CompositingRecursionData&, bool& layersChanged, bool& descendantHas3DTransform, Vector<RenderLayer*>& unclippedDescendants);
 
@@ -319,9 +312,9 @@ private:
     int m_compositedLayerCount;
     bool m_showRepaintCounter;
 
-    // FIXME: This should absolutely not be mutable.
-    mutable bool m_needsToRecomputeCompositingRequirements;
-    bool m_needsToUpdateLayerTreeGeometry;
+    // When true, we have to wait until layout has happened before we can decide whether to enter compositing mode,
+    // because only then do we know the final size of plugins and iframes.
+    mutable bool m_reevaluateCompositingAfterLayout;
 
     bool m_compositing;
     bool m_compositingLayersNeedRebuild;