Incorporate ComputedStyle::hasTransform when diffing transform styles.

third_party/WebKit/Source/core/paint/PaintLayerTest.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/PaintLayer.h"
 
 #include "core/html/HTMLIFrameElement.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
@@ skipping 813 matching lines @@
 
   EXPECT_EQ(LayoutPoint(-150, 50), spanner->location());
   EXPECT_EQ(LayoutPoint(100, 100), extraLayer->location());
   // -60 = 2nd-column-x(40) - scroll-offset-x(200) + x-location(100)
   // 20 = y-location(100) - column-height(80)
   EXPECT_EQ(LayoutPoint(-60, 20),
             extraLayer->visualOffsetFromAncestor(columns));
   EXPECT_EQ(LayoutPoint(-150, 50), spanner->visualOffsetFromAncestor(columns));
 }
 
+TEST_P(PaintLayerTest, PaintLayerTransformUpdatedOnStyleTransformAnimation) {
+  setBodyInnerHTML("<div id='target' style='will-change: transform'></div>");
+
+  LayoutObject* targetObject =
+      document().getElementById("target")->layoutObject();
+  PaintLayer* targetPaintLayer = toLayoutBoxModelObject(targetObject)->layer();
+  EXPECT_EQ(nullptr, targetPaintLayer->transform());
+
+  RefPtr<ComputedStyle> oldStyle =
+      ComputedStyle::clone(targetObject->styleRef());
+  ComputedStyle* newStyle = targetObject->mutableStyle();
+  newStyle->setHasCurrentTransformAnimation();
+  targetPaintLayer->updateTransform(oldStyle.get(), *newStyle);
+
+  EXPECT_NE(nullptr, targetPaintLayer->transform());
+}
+
 }  // namespace blink