Remove force-update when visual rects change

third_party/WebKit/Source/core/paint/PaintInvalidator.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintInvalidator.h"
 
 #include "core/editing/FrameSelection.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
@@ skipping 416 matching lines @@
           PaintInvalidatorContext::ForcedSubtreeSVGResourceChange;
       break;
     default:
       break;
   }
 
   if (context.oldLocation != context.newLocation) {
     context.forcedSubtreeInvalidationFlags |=
         PaintInvalidatorContext::ForcedSubtreeInvalidationChecking;
   }
-
-  // TODO(crbug.com/490725): This is a workaround for the bug, to force
-  // descendant to update visual rects on clipping change.
-  if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled() &&
-      context.oldVisualRect != context.newVisualRect
-      // Note that isLayoutView() below becomes unnecessary after the launch of
-      // root layer scrolling.
-      && (object.hasOverflowClip() || object.isLayoutView()) &&
-      !toLayoutBox(object).usesCompositedScrolling())
-    context.forcedSubtreeInvalidationFlags |=
-        PaintInvalidatorContext::ForcedSubtreeInvalidationRectUpdate;

[Xianzhu, 2017/02/21 19:31:00]

We still need to set the flag on ancestor clip change, now in PrePaintTreeWalk.

This patch fails with a modified version of
paint/invalidation/clip-unclip-and-change.html. I create a new patch based on
this CL. It includes the modified test case and fixes the issue:
https://codereview.chromium.org/2702883002/.

[chrishtr, 2017/02/27 21:15:36]

Is this test exhibiting a case where the paint invalidator context
was not properly updated for the item which changes its clip?

 }
 
 void PaintInvalidator::processPendingDelayedPaintInvalidations() {
   for (auto target : m_pendingDelayedPaintInvalidations)
     target->getMutableForPainting().setShouldDoFullPaintInvalidation(
         PaintInvalidationDelayedFull);
 }
 
 }  // namespace blink