cc:: Use clip tree instead of layer tree during hit testing

cc/trees/layer_tree_impl_unittest.cc

Index: cc/trees/layer_tree_impl_unittest.cc
diff --git a/cc/trees/layer_tree_impl_unittest.cc b/cc/trees/layer_tree_impl_unittest.cc
index b6cf7f23148086434762b7d1c74c644493137d9c..3b35cfcccaf79c0fb0a846160c347c9bd8d53432 100644
--- a/cc/trees/layer_tree_impl_unittest.cc
+++ b/cc/trees/layer_tree_impl_unittest.cc
@@ -380,6 +380,41 @@ TEST_F(LayerTreeImplTest, HitTestingForSingleRotatedLayer) {
   ASSERT_FALSE(result_layer);
 }
 
+TEST_F(LayerTreeImplTest, HitTestingSiblings) {
+  // This tests hit testing when the test point hits only one of the siblings.
+  gfx::Transform identity_matrix;
+  scoped_ptr<LayerImpl> root = LayerImpl::Create(host_impl().active_tree(), 1);
+  SetLayerPropertiesForTesting(root.get(), identity_matrix, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(100, 100), true, false,
+                               true);
+  scoped_ptr<LayerImpl> child1 =
+      LayerImpl::Create(host_impl().active_tree(), 2);
+  SetLayerPropertiesForTesting(child1.get(), identity_matrix, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(25, 25), true, false,
+                               false);
+  child1->SetMasksToBounds(true);
+  child1->SetDrawsContent(true);
+  scoped_ptr<LayerImpl> child2 =
+      LayerImpl::Create(host_impl().active_tree(), 3);
+  SetLayerPropertiesForTesting(child2.get(), identity_matrix, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(75, 75), true, false,
+                               false);
+  child2->SetMasksToBounds(true);
+  child2->SetDrawsContent(true);
+  root->AddChild(std::move(child1));
+  root->AddChild(std::move(child2));
+
+  host_impl().SetViewportSize(root->bounds());
+  host_impl().active_tree()->SetRootLayer(std::move(root));
+  host_impl().UpdateNumChildrenAndDrawPropertiesForActiveTree();
+
+  gfx::PointF test_point(50.f, 50.f);
+  LayerImpl* result_layer =
+      host_impl().active_tree()->FindLayerThatIsHitByPoint(test_point);
+  ASSERT_TRUE(result_layer);
+  EXPECT_EQ(3, result_layer->id());
+}
+
 TEST_F(LayerTreeImplTest, HitTestingForSinglePerspectiveLayer) {
   scoped_ptr<LayerImpl> root =
       LayerImpl::Create(host_impl().active_tree(), 12345);