Update subtree paint properties when preserve-3d changes

third_party/WebKit/Source/core/paint/PaintPropertyTreeUpdateTests.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/html/HTMLIFrameElement.h"
 #include "core/paint/PaintPropertyTreeBuilderTest.h"
 #include "core/paint/PaintPropertyTreePrinter.h"
 
 namespace blink {
 
@@ skipping 704 matching lines @@
 
   auto* newStyle = document().createElement("style");
   newStyle->setTextContent("::-webkit-scrollbar {width: 40px; height: 40px}");
   document().body()->appendChild(newStyle);
 
   document().view()->updateAllLifecyclePhases();
   EXPECT_EQ(overflowClip, container->paintProperties()->overflowClip());
   EXPECT_EQ(FloatSize(60, 60), overflowClip->clipRect().rect().size());
 }
 
+TEST_P(PaintPropertyTreeUpdateTest, Preserve3DChange) {
+  setBodyInnerHTML(
+      "<div id='parent'>"
+      "  <div id='child' style='transform: translate3D(1px, 2px, 3px)'></div>"
+      "</div>");
+
+  auto* child = getLayoutObjectByElementId("child");
+  auto* transform = child->paintProperties()->transform();
+  EXPECT_TRUE(transform->flattensInheritedTransform());
+
+  document().getElementById("parent")->setAttribute(
+      HTMLNames::styleAttr, "transform-style: preserve-3d");
+  document().view()->updateAllLifecyclePhases();
+  EXPECT_EQ(transform, child->paintProperties()->transform());
+  EXPECT_FALSE(transform->flattensInheritedTransform());
+}
+
 }  // namespace blink