Update transform paint property's transform-offset on element size changes

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

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index fb3c6cb78c8784e627960e94620930bb96a59171..a0433a9ac96c09ed46b3c831ff328fc6113dc81e 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -1703,12 +1703,18 @@ void LayoutBox::frameRectChanged() {
   if (!needsLayout())
     setMayNeedPaintInvalidation();
 
-  // The overflow clip paint property depends on the border box rect through
-  // overflowClipRect(). The border box rect's size equals the frame rect's
-  // size, so we trigger a paint property update when the framerect changes.
-  if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled() &&
-      shouldClipOverflow())
-    setNeedsPaintPropertyUpdate();
+  if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled()) {
+    if (shouldClipOverflow()) {
+      // The overflow clip paint property depends on the border box rect through
+      // overflowClipRect(). The border box rect's size equals the frame rect's
+      // size so we trigger a paint property update when the frame rect changes.
+      setNeedsPaintPropertyUpdate();
+    } else if (hasTransformRelatedProperty()) {

[Xianzhu, 2016/12/22 05:10:11]

I think the CL is fine to fix the layout test failure, but might need some
follow-ups:
- The above condition seems not to cover all cases that we'll create a transform
node, e.g. will-change: opacity.
- We could have more accurate conditions to trigger
setNeedsPaintPropertyUpdate() for only transform related properties with percent
or calculated values.
- We could separate handling of location change and size change (I have an
ongoing CL for this).

+      // The transform paint property depends on the frame rect due to
+      // transform-origin so we trigger an update when the frame rect changes.
+      setNeedsPaintPropertyUpdate();
+    }
+  }
 }
 
 bool LayoutBox::intersectsVisibleViewport() const {