Improve performance when calling PaintLayer::setNeedsRepaint()

third_party/WebKit/Source/core/layout/LayoutObject.cpp

Index: third_party/WebKit/Source/core/layout/LayoutObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.cpp b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
index a53c64682040896e7433533b73de6f314ee71f60..816d88cb044294ae24d0cea6294c5024e91ff7c3 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -1281,6 +1281,8 @@ void LayoutObject::invalidatePaintRectangle(const LayoutRect& rect) const
     const LayoutBoxModelObject* paintInvalidationContainer = invalidatePaintRectangleInternal(rect);
     if (paintInvalidationContainer)
         invalidateDisplayItemClients(*paintInvalidationContainer, PaintInvalidationRectangle);
+    if (PaintLayer* enclosingLayer = this->enclosingLayer())
+        enclosingLayer->setNeedsRepaint();
 }
 
 void LayoutObject::invalidatePaintRectangleNotInvalidatingDisplayItemClients(const LayoutRect& r) const
@@ -1430,13 +1432,16 @@ PaintInvalidationReason LayoutObject::invalidatePaintIfNeeded(PaintInvalidationS
         // mutation, but incurs no pixel difference (i.e. bounds stay the same) so no rect-based
         // invalidation is issued. See crbug.com/508383 and crbug.com/515977.
         // This is a workaround to force display items to update paint offset.
-        if (!RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled() && paintInvalidationState.forcedSubtreeInvalidationWithinContainer())
+        if (!RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled() && paintInvalidationState.forcedSubtreeInvalidationWithinContainer()) {
             invalidateDisplayItemClients(paintInvalidationContainer, invalidationReason);
+            paintInvalidationState.enclosingLayer().setNeedsRepaint();
+        }
 
         return invalidationReason;
     }
 
     invalidateDisplayItemClients(paintInvalidationContainer, invalidationReason);
+    paintInvalidationState.enclosingLayer().setNeedsRepaint();
 
     if (invalidationReason == PaintInvalidationIncremental) {
         incrementallyInvalidatePaint(paintInvalidationContainer, oldBounds, newBounds, newLocation);
@@ -3405,11 +3410,20 @@ void LayoutObject::invalidateDisplayItemClientsIncludingNonCompositingDescendant
 
     traverseNonCompositingDescendants(const_cast<LayoutObject&>(*this), [&paintInvalidationContainer, paintInvalidationReason](LayoutObject& object) {
         object.invalidateDisplayItemClients(*paintInvalidationContainer, paintInvalidationReason);
+        if (object.hasLayer())
+            toLayoutBoxModelObject(object).layer()->setNeedsRepaint();
     });
 }
 
 void LayoutObject::invalidatePaintOfPreviousPaintInvalidationRect(const LayoutBoxModelObject& paintInvalidationContainer, PaintInvalidationReason reason)
 {
+    invalidatePaintOfPreviousPaintInvalidationRectNotSettingLayerNeedsRepaint(paintInvalidationContainer, reason);
+    if (PaintLayer* enclosingLayer = this->enclosingLayer())
+        enclosingLayer->setNeedsRepaint();
+}
+
+void LayoutObject::invalidatePaintOfPreviousPaintInvalidationRectNotSettingLayerNeedsRepaint(const LayoutBoxModelObject& paintInvalidationContainer, PaintInvalidationReason reason)
+{

[chrishtr, 2016/01/14 18:51:13]

This looks like a copy of the old code. I expected to see deleted lines where
setNeedsRepaint() was removed.

[Xianzhu, 2016/01/14 19:19:08]

Now invalidateDisplayItemClients() doesn't set layers needs repaint, but the
callers do instead. This function becomes 'NotSettingLayerNeedsRepaint' because
of the change of invalidateDisplayItemClients().

[chrishtr, 2016/01/15 00:02:21]

I understand the goal, but can't find where you are changing it to not
setNeedsRepaint where it was doing so before. You changed line 3434 to
invalidatePaintOfPreviousPaintInvalidationRectNotSettingLayerNeedsRepaint(), but

as far as I can tell, the definition of
invalidatePaintOfPreviousPaintInvalidationRectNotSettingLayerNeedsRepaint() is
the same
as it was before.. ?

     // These disablers are valid because we want to use the current compositing/invalidation status.
     DisablePaintInvalidationStateAsserts invalidationDisabler;
     DisableCompositingQueryAsserts compositingDisabler;
@@ -3431,7 +3445,9 @@ void LayoutObject::invalidatePaintIncludingNonCompositingDescendants()
     // Since we're only painting non-composited layers, we know that they all share the same paintInvalidationContainer.
     const LayoutBoxModelObject& paintInvalidationContainer = containerForPaintInvalidation();
     traverseNonCompositingDescendants(*this, [&paintInvalidationContainer](LayoutObject& object) {
-        object.invalidatePaintOfPreviousPaintInvalidationRect(paintInvalidationContainer, PaintInvalidationLayer);
+        object.invalidatePaintOfPreviousPaintInvalidationRectNotSettingLayerNeedsRepaint(paintInvalidationContainer, PaintInvalidationLayer);
+        if (object.hasLayer())
+            toLayoutBoxModelObject(object).layer()->setNeedsRepaint();
     });
 }