Check rect under-invalidations

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

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. 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 192 matching lines @@
 
     typedef HashMap<int, int> RenderingContextMap;
     PassRefPtr<JSONObject> layerTreeAsJSON(LayerTreeFlags, RenderingContextMap&) const;
 
     int paintCount() const { return m_paintCount; }
 
     // Return a string with a human readable form of the layer tree, If debug is true
     // pointers for the layers and timing data will be included in the returned string.
     String layerTreeAsText(LayerTreeFlags = LayerTreeNormal) const;
 
-    bool isTrackingPaintInvalidations() const { return m_client->isTrackingPaintInvalidations(); }
+    void setTracksPaintInvalidations(bool);
+    bool isTrackingOrCheckingPaintInvalidations() const

[pdr., 2016/06/09 19:21:44]

I worry that the checking part will be very slow on debug bots. Do we need this
to run the pixel verification continuously? I am wondering if we could just do
the pixel verification manually using the flag.

[Xianzhu, 2016/06/09 20:47:44]

If the flag is not enabled, we do pixel verification only in repaint tests which
explicitly track paint invalidations. Most of the tests just track paint
invalidations for just 1 or 2 paintings.

Compared timings of running layout tests under fast/repaint with and without
this patch with debug builds:

With this patch:
12:59:58.361 15624 PER TEST TIME IN TESTSHELL (seconds):
12:59:58.361 15624   Median:           0.590
12:59:58.361 15624   Mean:             0.523
12:59:58.361 15624   90th percentile:  0.776
12:59:58.361 15624   99th percentile:  1.118
12:59:58.361 15624   Standard dev:     0.045
slowest: fast/repaint/4774354.html took 1.5 seconds

Without this patch:
13:35:42.968 23271 PER TEST TIME IN TESTSHELL (seconds):
13:35:42.968 23271   Median:           0.615
13:35:42.968 23271   Mean:             0.540
13:35:42.968 23271   90th percentile:  0.793
13:35:42.968 23271   99th percentile:  1.157
13:35:42.968 23271   Standard dev:     0.052
slowest: fast/repaint/4774354.html took 1.5 seconds

They are basically the same indicating that pixel verification contributes
little to the time.

+    {
+#if DCHECK_IS_ON()
+        if (RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled())
+            return true;
+#endif
+        return m_isTrackingPaintInvalidations;
+    }
+
     void resetTrackedPaintInvalidations();
     bool hasTrackedPaintInvalidations() const;
-    void trackPaintInvalidation(const DisplayItemClient&, const FloatRect&, PaintInvalidationReason);
+    void trackPaintInvalidation(const DisplayItemClient&, const IntRect&, PaintInvalidationReason);
 
     void addLinkHighlight(LinkHighlight*);
     void removeLinkHighlight(LinkHighlight*);
     // Exposed for tests
     unsigned numLinkHighlights() { return m_linkHighlights.size(); }
     LinkHighlight* getLinkHighlight(int i) { return m_linkHighlights[i]; }
 
     void setScrollableArea(ScrollableArea*, bool isViewport);
     ScrollableArea* getScrollableArea() const { return m_scrollableArea; }
 
@@ skipping 58 matching lines @@
     // Helper functions used by settors to keep layer's the state consistent.
     void updateChildList();
     void updateLayerIsDrawable();
     void updateContentsRect();
 
     void setContentsTo(WebLayer*);
     void setupContentsLayer(WebLayer*);
     void clearContentsLayerIfUnregistered();
     WebLayer* contentsLayerIfRegistered();
 
+#if DCHECK_IS_ON()
+    PassRefPtr<SkPicture> capturePicture();
+    void checkUnderPaintInvalidations(const SkPicture&);
+#endif
+
     GraphicsLayerClient* m_client;
 
     // Offset from the owning layoutObject
     DoubleSize m_offsetFromLayoutObject;
 
     // Position is relative to the parent GraphicsLayer
     FloatPoint m_position;
     FloatSize m_size;
 
     TransformationMatrix m_transform;
@@ skipping 13 matching lines @@
     bool m_contentsVisible : 1;
     bool m_isRootForIsolatedGroup : 1;
 
     bool m_hasScrollParent : 1;
     bool m_hasClipParent : 1;
 
     bool m_painted : 1;
     bool m_textPainted : 1;
     bool m_imagePainted : 1;
 
+    bool m_isTrackingPaintInvalidations : 1;
+
     GraphicsLayerPaintingPhase m_paintingPhase;
 
     Vector<GraphicsLayer*> m_children;
     GraphicsLayer* m_parent;
 
     GraphicsLayer* m_maskLayer; // Reference to mask layer. We don't own this.
     GraphicsLayer* m_contentsClippingMaskLayer; // Reference to clipping mask layer. We don't own this.
 
     // A layer that replicates this layer. We only allow one, for now.
     // The replica is not parented; this is the primary reference to it.
@@ skipping 30 matching lines @@
 };
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the blink namespace for ease of invocation from gdb.
 void PLATFORM_EXPORT showGraphicsLayerTree(const blink::GraphicsLayer*);
 #endif
 
 #endif // GraphicsLayer_h