Add StyleDifference::needsVisualRectUpdate

third_party/WebKit/Source/core/style/ComputedStyle.cpp

Index: third_party/WebKit/Source/core/style/ComputedStyle.cpp
diff --git a/third_party/WebKit/Source/core/style/ComputedStyle.cpp b/third_party/WebKit/Source/core/style/ComputedStyle.cpp
index 1a07e189c1ca942ee2389360984bf78d3f62f0f8..f08f94f3284e29691096fd57cd6f45baf3b27a9e 100644
--- a/third_party/WebKit/Source/core/style/ComputedStyle.cpp
+++ b/third_party/WebKit/Source/core/style/ComputedStyle.cpp
@@ -561,6 +561,9 @@ StyleDifference ComputedStyle::visualInvalidationDiff(
   else if (diffNeedsPaintInvalidationObject(other))
     diff.setNeedsPaintInvalidationObject();
 
+  if (diffNeedsVisualRectUpdate(other))
+    diff.setNeedsVisualRectUpdate();
+
   updatePropertySpecificDifferences(other, diff);
 
   // The following condition needs to be at last, because it may depend on
@@ -1004,6 +1007,21 @@ bool ComputedStyle::diffNeedsPaintInvalidationObjectForPaintImage(
   return false;
 }
 
+// This doesn't include conditions needing layout or overflow recomputation
+// which implies visual rect update.
+bool ComputedStyle::diffNeedsVisualRectUpdate(
+    const ComputedStyle& other) const {
+  // Visual rect is empty if visibility is hidden.
+  if (visibility() != other.visibility())

[pdr., 2017/03/20 21:23:04]

Where was this logic before this patch? Can we remove the old code that was
detecting visibility changes?

[Xianzhu, 2017/03/20 22:26:35]

This is to make https://codereview.chromium.org/2732573003/ work. Previously
visibility change only caused needsPaintInvalidationObject which just caused
shouldDoFullPaintInvalidationWithoutGeometryChange().

Visibility affects visual rects through the visibility conditions in
localVisualRect() methods.

In the new patch I removed visibility change condition from
diffNeedsPaintInvalidationObject because visibility changes cause either empty
or non-empty visual rects, and diffNeedsVisualRectUpdate() is good.

+    return true;
+
+  // Need to update visual rect of the resizer.
+  if (resize() != other.resize())

[pdr., 2017/03/20 21:23:04]

The old code seemed to check against RESIZE_NONE whereas this checks against
changes. Is that the optimization you're referring to in the change description?

[Xianzhu, 2017/03/20 22:26:35]

The old code always invalidates the whole box container resizer when the box is
resized. With this change we'll just incrementally invalidate the box if needed
and invalidate the resizer if needed.

paint/invalidation/textarea-appearance-none-resize-handle-expected.txt shows the
effect of the optimization.

Here I don't check RESIZE_NONE for safety of future changes about visual size of
resizer according to different resizer styles.

+    return true;
+
+  return false;
+}
+
 void ComputedStyle::updatePropertySpecificDifferences(
     const ComputedStyle& other,
     StyleDifference& diff) const {