Fix removing layers when the pipeline is not the owner

If cogl_pipeline_remove_layer is called on a copied pipeline to remove
a parent layer then it will still end up calling
_cogl_pipeline_remove_layer_difference on the layer. This function
was directly trying to remove the layer from the pipeline's list of
layer differences. However in the child pipeline the layer isn't in
the list because it is unchanged from its parent. The function had an
assertion to verify that this situation wasn't hit so in a debug build
it would just bail out.

This patch removes the assertion and changes it to only remove the
layer if it is owned by the pipeline. Otherwise it just sets the
COGL_PIPELINE_STATE_LAYERS difference as normal and decrements the
number of layers. This will cause it to successfully remove the layer
because either it is the last layer in which case it will be ignored
after n_layers is decreased or if it is in the middle of the list then
the subsequent layers will all be shifted down so there will be a
replacement layer difference.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 88e73dd93fa09a158064a946ab229591a5888b97)

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/conform/test-conform-main.c b/tests/conform/test-conform-main.c
index 02f428f8..aa2f746c 100644
--- a/tests/conform/test-conform-main.c
+++ b/tests/conform/test-conform-main.c
@@ -59,7 +59,7 @@ main (int argc, char **argv)
   ADD_TEST (test_depth_test, 0);
   ADD_TEST (test_color_mask, 0);
   ADD_TEST (test_backface_culling, TEST_REQUIREMENT_NPOT);
-  ADD_TEST (test_layer_remove, TEST_KNOWN_FAILURE);
+  ADD_TEST (test_layer_remove, 0);
 
   ADD_TEST (test_sparse_pipeline, 0);