Simplify incremental paint invalidation

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

 /*
  * Copyright (C) 2009 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 499 matching lines @@
   if (!tracking)
     return;
 
   if (RuntimeEnabledFeatures::paintUnderInvalidationCheckingEnabled())
     tracking->trackedRasterInvalidations.clear();
   else
     rasterInvalidationTrackingMap().remove(this);
 }
 
 bool GraphicsLayer::hasTrackedRasterInvalidations() const {
-  RasterInvalidationTracking* tracking =
-      rasterInvalidationTrackingMap().find(this);
-  if (tracking)
+  if (auto* tracking = getRasterInvalidationTracking())
     return !tracking->trackedRasterInvalidations.isEmpty();
   return false;
 }
 
+const RasterInvalidationTracking* GraphicsLayer::getRasterInvalidationTracking()
+    const {
+  return rasterInvalidationTrackingMap().find(this);
+}
+
 void GraphicsLayer::trackRasterInvalidation(const DisplayItemClient& client,
                                             const IntRect& rect,
                                             PaintInvalidationReason reason) {
   if (!isTrackingOrCheckingRasterInvalidations() || rect.isEmpty())
     return;
 
   RasterInvalidationTracking& tracking =
       rasterInvalidationTrackingMap().add(this);
 
   if (m_isTrackingRasterInvalidations) {
@@ skipping 753 matching lines @@
 void showGraphicsLayerTree(const blink::GraphicsLayer* layer) {
   if (!layer) {
     fprintf(stderr, "Cannot showGraphicsLayerTree for (nil).\n");
     return;
   }
 
   String output = layer->layerTreeAsText(blink::LayerTreeIncludesDebugInfo);
   fprintf(stderr, "%s\n", output.utf8().data());
 }
 #endif