Fix for bug where composited rotate3d should SLERP

cc/animation/transform_operations_unittest.cc

Index: cc/animation/transform_operations_unittest.cc
diff --git a/cc/animation/transform_operations_unittest.cc b/cc/animation/transform_operations_unittest.cc
index c5fb3c6b8160027c9e0672823a2e91c35b323b75..a5cf7ec96197a499f4c32f0542298bdd5d364b00 100644
--- a/cc/animation/transform_operations_unittest.cc
+++ b/cc/animation/transform_operations_unittest.cc
@@ -441,6 +441,42 @@ TEST(TransformOperationTest, LargeRotationsWithDifferentAxes) {
       expected, operations_to.Blend(operations_from, progress));
 }
 
+TEST(TransformOperationTest, RotationWithSlerpFromZeroDeg) {
+  TransformOperations operations_from;
+  operations_from.AppendRotate(0, 0, 1, 0);
+
+  TransformOperations operations_to;
+  operations_to.AppendRotate(0, 1, 0, 450);
+
+  SkMScalar progress = 0.5f;
+  gfx::Transform matrix_from;
+  matrix_from.RotateAbout(gfx::Vector3dF(0, 0, 1), 0);
+
+  gfx::Transform matrix_to;
+  matrix_to.RotateAbout(gfx::Vector3dF(0, 1, 0), 90);
+
+  gfx::Transform expected = matrix_to;
+  expected.Blend(matrix_from, progress);
+
+  EXPECT_TRANSFORMATION_MATRIX_EQ(
+      expected, operations_to.Blend(operations_from, progress));
+}
+
+TEST(TransformOperationTest, RotationWithoutSlerpFromZeroDeg) {
+  TransformOperations operations_from;
+  operations_from.AppendRotate(0, 0, 1, 0);
+
+  TransformOperations operations_to;
+  operations_to.AppendRotate(0, 0, 1, 450);
+
+  SkMScalar progress = 0.5f;
+  gfx::Transform expected;
+  expected.RotateAbout(gfx::Vector3dF(0, 0, 1), 225);
+
+  EXPECT_TRANSFORMATION_MATRIX_EQ(
+      expected, operations_to.Blend(operations_from, progress));
+}
+
 TEST(TransformOperationTest, BlendRotationFromIdentity) {
   ScopedVector<TransformOperations> identity_operations;
   GetIdentityOperations(&identity_operations);