Update perspective paint properties on perspective-origin 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 6c5c3933c8550867b15c31f74fc00c9f1c702ef3..480406b8913d4fd9f3456f0deb1c274eca9c4453 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -1709,10 +1709,12 @@ void LayoutBox::frameRectChanged() {
       // 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 (styleRef().hasTransform()) {
-      // The transform paint property's origin depends on the frame rect because
-      // transform-origin can be sized with lengths relative to the frame rect.
-      // See: PaintPropertyTreeBuilder::updateTransform(...).
+    } else if (styleRef().hasTransform() || styleRef().hasPerspective()) {
+      // Both transform-origin and perspective-origin can change if they use
+      // relative lengths and the frame rect changes.
+      // See: PaintPropertyTreeBuilder's updateTransform and updatePerspective.
+      // TODO(pdr): We only need to update properties if the origin is specified
+      // with relative lengths (e.g., percentage).

[Xianzhu, 2016/12/22 21:55:15]

Nit: Other transform components can also be relative lengths, e.g.
translateX(10%), which is also covered by this condition. Please update comments
to mention this.

       setNeedsPaintPropertyUpdate();
     }
   }