cc : Remove DCHECK in TransformTree::ComputeTranslation

cc/trees/layer_tree_host_common_unittest.cc

 // Copyright 2011 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 "cc/trees/layer_tree_host_common.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 9332 matching lines @@
 
   node = tree.Node(between_targets->transform_tree_index());
   EXPECT_EQ(node->surface_contents_scale, gfx::Vector2dF(1.f, 1.f));
 
   node = tree.Node(render_surface2->transform_tree_index());
   EXPECT_EQ(node->surface_contents_scale, gfx::Vector2dF(2.f, 2.f));
 
   EXPECT_EQ(gfx::Rect(15, 15), test_layer->visible_layer_rect());
 }
 
+TEST_F(LayerTreeHostCommonTest, NoisyTransform) {

[Alexander Potapenko, 2016/08/25 09:43:28]

Did you intend to submit this test as well?

[jaydasika, 2016/08/26 17:39:31]

Yes. To ensure that no one adds back the DCHECK this CL removes.

+  LayerImpl* root = root_layer_for_testing();
+  LayerImpl* render_surface = AddChild<LayerImpl>(root);
+  LayerImpl* scroll_child = AddChild<LayerImpl>(render_surface);
+  LayerImpl* scroll_clip = AddChild<LayerImpl>(render_surface);
+  LayerImpl* scroll_parent = AddChild<LayerImpl>(scroll_clip);
+
+  scroll_child->test_properties()->scroll_parent = scroll_parent;
+  scroll_parent->test_properties()->scroll_children =
+      base::MakeUnique<std::set<LayerImpl*>>();
+  scroll_parent->test_properties()->scroll_children->insert(scroll_child);
+  scroll_parent->SetScrollClipLayer(scroll_clip->id());
+
+  scroll_parent->SetDrawsContent(true);
+  scroll_child->SetDrawsContent(true);
+  render_surface->test_properties()->force_render_surface = true;
+
+  // A noisy transform that's invertible.
+  gfx::Transform transform;
+  transform.matrix().setDouble(0, 0, 6.12323e-17);
+  transform.matrix().setDouble(0, 2, 1);
+  transform.matrix().setDouble(2, 2, 6.12323e-17);
+  transform.matrix().setDouble(2, 0, -1);
+
+  scroll_child->test_properties()->transform = transform;
+  render_surface->test_properties()->transform = transform;
+
+  root->SetBounds(gfx::Size(30, 30));
+  scroll_child->SetBounds(gfx::Size(30, 30));
+  scroll_parent->SetBounds(gfx::Size(30, 30));
+  ExecuteCalculateDrawProperties(root);
+
+  gfx::Transform expected;
+  expected.matrix().setDouble(0, 0, 3.749395e-33);
+  expected.matrix().setDouble(0, 2, 6.12323e-17);
+  expected.matrix().setDouble(2, 0, -1);
+  expected.matrix().setDouble(2, 2, 6.12323e-17);
+  EXPECT_TRANSFORMATION_MATRIX_EQ(expected,
+                                  scroll_child->ScreenSpaceTransform());
+}
+
 TEST_F(LayerTreeHostCommonTest, LargeTransformTest) {
   LayerImpl* root = root_layer_for_testing();
   LayerImpl* render_surface1 = AddChild<LayerImpl>(root);
   LayerImpl* child = AddChild<LayerImpl>(render_surface1);
 
   child->SetDrawsContent(true);
   child->SetMasksToBounds(true);
 
   gfx::Transform large_transform;
   large_transform.Scale(99999999999999999999.f, 99999999999999999999.f);
@@ skipping 405 matching lines @@
   EXPECT_EQ(scroll_child6.id, grand_child10->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, parent3->scroll_tree_index());
   EXPECT_EQ(scroll_child7.id, child8->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, parent4->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, child9->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, grand_child12->scroll_tree_index());
 }
 
 }  // namespace
 }  // namespace cc