Initial scroll-blocks-on compositor integration

Source/core/rendering/compositing/CompositingRequirementsUpdater.cpp

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 172 matching lines @@
 
 CompositingRequirementsUpdater::~CompositingRequirementsUpdater()
 {
 }
 
 void CompositingRequirementsUpdater::update(RenderLayer* root)
 {
     TRACE_EVENT0("blink", "CompositingRequirementsUpdater::updateRecursive");
 
     // Go through the layers in presentation order, so that we can compute which RenderLayers need compositing layers.
-    // FIXME: we could maybe do this and the hierarchy udpate in one pass, but the parenting logic would be more complex.
+    // FIXME: we could maybe do this and the hierarchy update in one pass, but the parenting logic would be more complex.
     RecursionData recursionData(root);
     OverlapMap overlapTestRequestMap;
     bool saw3DTransform = false;
 
     // FIXME: Passing these unclippedDescendants down and keeping track
     // of them dynamically, we are requiring a full tree walk. This
     // should be removed as soon as proper overlap testing based on
     // scrolling and animation bounds is implemented (crbug.com/252472).
     Vector<RenderLayer*> unclippedDescendants;
     IntRect absoluteDecendantBoundingBox;
@@ skipping 229 matching lines @@
 
         descendantHas3DTransform |= anyDescendantHas3DTransform || layer->has3DTransform();
     }
 
     // At this point we have finished collecting all reasons to composite this layer.
     layer->setCompositingReasons(reasonsToComposite);
 
 }
 
 } // namespace blink