Implement transform/clip support for Android WebView.

cc/layers/layer_position_constraint_unittest.cc

Index: cc/layers/layer_position_constraint_unittest.cc
diff --git a/cc/layers/layer_position_constraint_unittest.cc b/cc/layers/layer_position_constraint_unittest.cc
index af1af4ead0f3d44c518c1f8b76353b52fa05a533..37f38afb28c38b387660a83077ab8c02b74d29ea 100644
--- a/cc/layers/layer_position_constraint_unittest.cc
+++ b/cc/layers/layer_position_constraint_unittest.cc
@@ -50,6 +50,7 @@ void ExecuteCalculateDrawProperties(LayerImpl* root_layer,
   LayerTreeHostCommon::CalculateDrawProperties(
       root_layer,
       device_viewport_size,
+      gfx::Transform(),
       device_scale_factor,
       page_scale_factor,
       page_scale_application_layer,
@@ -1030,70 +1031,5 @@ TEST_F(LayerPositionConstraintTest,
                                   grand_child->draw_transform());
 }
 
-TEST_F(LayerPositionConstraintTest,
-     ScrollCompensationForFixedPositionLayerThatHasNoContainer) {

[enne (OOO), 2013/06/04 17:26:03]

What do you mean by "we don't ever plan to structure the tree this way"?

[aelias_OOO_until_Jul13, 2013/06/04 17:54:20]

A fixed-pos layer will always have a clip layer above it in practice, so I
figured we could leave the case where there's no clip layer having undefined
behavior.

[danakj, 2013/06/04 18:02:50]

Until the UI compositor does it? Should that be a consideration?

[aelias_OOO_until_Jul13, 2013/06/04 22:18:27]

Anyway, since all we care about is some kind of consistent behavior, I brought
this back and changed this to test that fixed-pos elements are affixed to the
root layer instead.  I also simplified the LTHCommon code to avoid needing to
support the container == NULL case, passing the root_layer as starting
fixed_container instead.

-  // This test checks scroll compensation when a fixed-position layer does not
-  // find any ancestor that is a "containerForFixedPositionLayers". In this
-  // situation, the layer should be fixed to the viewport -- not the root_layer,
-  // which may have transforms of its own.
-  LayerImpl* child = root_->children()[0];
-  LayerImpl* grand_child = child->children()[0];
-
-  gfx::Transform rotation_by_z;
-  rotation_by_z.RotateAboutZAxis(90.0);
-
-  root_->SetTransform(rotation_by_z);
-  grand_child->SetPositionConstraint(fixed_to_top_left_);
-
-  // Case 1: root scroll delta of 0, 0
-  root_->SetScrollDelta(gfx::Vector2d(0, 0));
-  ExecuteCalculateDrawProperties(root_.get());
-
-  gfx::Transform identity_matrix;
-
-  EXPECT_TRANSFORMATION_MATRIX_EQ(identity_matrix, child->draw_transform());
-  EXPECT_TRANSFORMATION_MATRIX_EQ(identity_matrix,
-                                  grand_child->draw_transform());
-
-  // Case 2: root scroll delta of 10, 10
-  root_->SetScrollDelta(gfx::Vector2d(10, 20));
-  ExecuteCalculateDrawProperties(root_.get());
-
-  // The child is affected by scroll delta, but it is already implcitly
-  // accounted for by the child's target surface (i.e. the root render surface).
-  // The grand_child is not affected by the scroll delta, so its draw transform
-  // needs to explicitly inverse-compensate for the scroll that's embedded in
-  // the target surface.
-  gfx::Transform expected_grand_child_transform;
-  expected_grand_child_transform.PreconcatTransform(Inverse(rotation_by_z));
-  // explicit cancelling out the scroll delta that gets embedded in the fixed
-  // position layer's surface.
-  expected_grand_child_transform.Translate(10.0, 20.0);
-  expected_grand_child_transform.PreconcatTransform(rotation_by_z);
-
-  EXPECT_TRANSFORMATION_MATRIX_EQ(identity_matrix, child->draw_transform());
-  EXPECT_TRANSFORMATION_MATRIX_EQ(expected_grand_child_transform,
-                                  grand_child->draw_transform());
-
-
-  // Case 3: fixed-container size delta of 20, 20
-  root_->SetFixedContainerSizeDelta(gfx::Vector2d(20, 20));
-  ExecuteCalculateDrawProperties(root_.get());
-
-  // Top-left fixed-position layer should not be affected by container size.
-  EXPECT_TRANSFORMATION_MATRIX_EQ(identity_matrix, child->draw_transform());
-  EXPECT_TRANSFORMATION_MATRIX_EQ(expected_grand_child_transform,
-                                  grand_child->draw_transform());
-
-  // Case 4: Bottom-right fixed-position layer.
-  grand_child->SetPositionConstraint(fixed_to_bottom_right_);
-  ExecuteCalculateDrawProperties(root_.get());
-
-  // Root layer is not the fixed-container anyway.
-  EXPECT_TRANSFORMATION_MATRIX_EQ(identity_matrix, child->draw_transform());
-  EXPECT_TRANSFORMATION_MATRIX_EQ(expected_grand_child_transform,
-                                  grand_child->draw_transform());
-}
-
 }  // namespace
 }  // namespace cc