Slimming Paint phase 2 compositing algorithm plumbing

Source/core/compositing/DisplayListCompositingBuilderTest.cpp

+// Copyright 2015 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 "config.h"
+#include "core/compositing/DisplayListCompositingBuilder.h"
+
+#include "platform/RuntimeEnabledFeatures.h"
+#include <gtest/gtest.h>
+
+namespace blink {
+
+class DisplayListCompositingBuilderTest : public ::testing::Test {
+public:
+    DisplayListCompositingBuilderTest()
+        : m_originalSlimmingPaintV2Enabled(RuntimeEnabledFeatures::slimmingPaintV2Enabled()) { }
+
+private:
+    void SetUp() override
+    {
+        ASSERT_TRUE(RuntimeEnabledFeatures::slimmingPaintEnabled());
+        RuntimeEnabledFeatures::setSlimmingPaintV2Enabled(true);
+    }
+
+    void TearDown() override
+    {
+        RuntimeEnabledFeatures::setSlimmingPaintV2Enabled(m_originalSlimmingPaintV2Enabled);
+    }
+
+    bool m_originalSlimmingPaintV2Enabled;
+};
+
+TEST_F(DisplayListCompositingBuilderTest, BasicTransformPropertyTree)
+{
+    OwnPtr<DisplayItemList> displayItemList = DisplayItemList::create();
+    DisplayListDiff displayListDiff;
+    displayItemList->commitNewDisplayItems(&displayListDiff);
+
+    DisplayListCompositingBuilder compositingBuilder(*displayItemList, displayListDiff);
+    CompositedDisplayList compositedDisplayList;
+    compositingBuilder.build(compositedDisplayList);
+
+    const auto& tree = *compositedDisplayList.transformTree;
+    ASSERT_EQ(1u, tree.nodeCount());
+    EXPECT_TRUE(tree.nodeAt(0).isRoot());
+    EXPECT_TRUE(tree.nodeAt(0).matrix.isIdentity());
+}
+
+} // namespace blink