[SPv2] Support composited plugins via foreign layers.

BUG=587970
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/bf29b13a060e17f0e1cf96886ab1c798f7d54cc8
Cr-Commit-Position: refs/heads/master@{#378117}

Committed: https://crrev.com/c5a5aaba0445bf16820fdf0a5e0093f98e06dd23
Cr-Commit-Position: refs/heads/master@{#378148}

Review URL: https://codereview.chromium.org/1714153002

Cr-Commit-Position: refs/heads/master@{#378586}
diff --git a/third_party/WebKit/LayoutTests/TestExpectations b/third_party/WebKit/LayoutTests/TestExpectations
index 3b0c714..baff4924 100644
--- a/third_party/WebKit/LayoutTests/TestExpectations
+++ b/third_party/WebKit/LayoutTests/TestExpectations
@@ -449,6 +449,8 @@
 crbug.com/537409 virtual/spv2/svg/as-image/svg-image-with-data-uri.html [ Pass ]
 crbug.com/587236 virtual/spv2/compositing/backface-visibility/backface-visibility-3d.html [ Pass ]
 crbug.com/587236 virtual/spv2/compositing/backface-visibility/backface-visibility-simple.html [ Pass ]
+crbug.com/587970 virtual/spv2/compositing/plugins/webplugin-alpha.html [ Pass ]
+crbug.com/587970 virtual/spv2/compositing/plugins/webplugin-no-alpha.html [ Pass ]
 
 # In imported/web-platform-tests/html/, we prefer checking in failure
 # expectation files. The following tests with [ Failure ] don't have failure