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diff --git a/Source/WebKit/chromium/tests/CCMathUtilTest.cpp b/Source/WebKit/chromium/tests/CCMathUtilTest.cpp
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+++ b/Source/WebKit/chromium/tests/CCMathUtilTest.cpp
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+/*
+ * Copyright (C) 2012 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1.  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ * 2.  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+
+#include "cc/CCMathUtil.h"
+
+#include "TransformationMatrix.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using namespace WebCore;
+
+namespace {
+
+TEST(CCMathUtilTest, verifyBackfaceVisibilityBasicCases)
+{
+    TransformationMatrix transform;
+
+    transform.makeIdentity();
+    EXPECT_FALSE(transform.isBackFaceVisible());
+
+    transform.makeIdentity();
+    transform.rotate3d(0, 80, 0);
+    EXPECT_FALSE(transform.isBackFaceVisible());
+
+    transform.makeIdentity();
+    transform.rotate3d(0, 100, 0);
+    EXPECT_TRUE(transform.isBackFaceVisible());
+
+    // Edge case, 90 degree rotation should return false.
+    transform.makeIdentity();
+    transform.rotate3d(0, 90, 0);
+    EXPECT_FALSE(transform.isBackFaceVisible());
+}
+
+TEST(CCMathUtilTest, verifyBackfaceVisibilityForPerspective)
+{
+    TransformationMatrix layerSpaceToProjectionPlane;
+
+    // This tests if isBackFaceVisible works properly under perspective transforms.
+    // Specifically, layers that may have their back face visible in orthographic
+    // projection, may not actually have back face visible under perspective projection.
+
+    // Case 1: Layer is rotated by slightly more than 90 degrees, at the center of the
+    //         prespective projection. In this case, the layer's back-side is visible to
+    //         the camera.
+    layerSpaceToProjectionPlane.makeIdentity();
+    layerSpaceToProjectionPlane.applyPerspective(1);
+    layerSpaceToProjectionPlane.translate3d(0, 0, 0);
+    layerSpaceToProjectionPlane.rotate3d(0, 100, 0);
+    EXPECT_TRUE(layerSpaceToProjectionPlane.isBackFaceVisible());
+
+    // Case 2: Layer is rotated by slightly more than 90 degrees, but shifted off to the
+    //         side of the camera. Because of the wide field-of-view, the layer's front
+    //         side is still visible.
+    //
+    //                       |<-- front side of layer is visible to perspective camera
+    //                    \  |            /
+    //                     \ |           /
+    //                      \|          /
+    //                       |         /
+    //                       |\       /<-- camera field of view
+    //                       | \     /
+    // back side of layer -->|  \   /
+    //                           \./ <-- camera origin
+    //
+    layerSpaceToProjectionPlane.makeIdentity();
+    layerSpaceToProjectionPlane.applyPerspective(1);
+    layerSpaceToProjectionPlane.translate3d(-10, 0, 0);
+    layerSpaceToProjectionPlane.rotate3d(0, 100, 0);
+    EXPECT_FALSE(layerSpaceToProjectionPlane.isBackFaceVisible());
+
+    // Case 3: Additionally rotating the layer by 180 degrees should of course show the
+    //         opposite result of case 2.
+    layerSpaceToProjectionPlane.rotate3d(0, 180, 0);
+    EXPECT_TRUE(layerSpaceToProjectionPlane.isBackFaceVisible());
+}
+
+} // namespace