4 files changed, 16 insertions, 0 deletions
diff --git a/layout/reftests/webm-video/reftest.list b/layout/reftests/webm-video/reftest.list
index 91532af2bb..a178f3e886 100644
--- a/layout/reftests/webm-video/reftest.list
+++ b/layout/reftests/webm-video/reftest.list
@@ -32,6 +32,7 @@ random == poster-12.html poster-ref-blue140x100.html
 == poster-13.html poster-ref-blue400x300.html
 == poster-15.html poster-ref-green70x30.html
 random-if(winWidget) random-if(cocoaWidget) == bug686957.html bug686957-ref.html # bug 922951 for OS X
+== webm-alpha.html webm-alpha-ref.html
 
 # Tests for <video src> with 'object-fit' & 'object-position':
 # These tests should be very similar to tests in our w3c-css/submitted/images3
diff --git a/layout/reftests/webm-video/webm-alpha-ref.html b/layout/reftests/webm-video/webm-alpha-ref.html
new file mode 100644
index 0000000000..6675a23a13
--- /dev/null
+++ b/layout/reftests/webm-video/webm-alpha-ref.html
@@ -0,0 +1,5 @@
+<!DOCTYPE HTML>
+<html>
+<body style="background:black;">
+</body>
+</html>
diff --git a/layout/reftests/webm-video/webm-alpha.html b/layout/reftests/webm-video/webm-alpha.html
new file mode 100644
index 0000000000..8c613b473d
--- /dev/null
+++ b/layout/reftests/webm-video/webm-alpha.html
@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+<html>
+<body style="background:black;">
+<!--
+    Test that if a WebM video has an alpha channel, it is displayed correctly.
+-->
+<video src="webm-alpha.webm">
+</video>
+</body>
+</html>
diff --git a/layout/reftests/webm-video/webm-alpha.webm b/layout/reftests/webm-video/webm-alpha.webm
new file mode 100644
index 0000000000..b6fe4d7b68
--- /dev/null
+++ b/layout/reftests/webm-video/webm-alpha.webm