Presentation API: implement .getAvalability() (Blink side).

LayoutTests/presentation/presentation-api.html

Index: LayoutTests/presentation/presentation-api.html
diff --git a/LayoutTests/presentation/presentation-api.html b/LayoutTests/presentation/presentation-api.html
index 663844295dfd3c7ee0fc593510ac283b67dad1e3..c3cbcd22ef968d0c77dc25084dccdc8078955c27 100644
--- a/LayoutTests/presentation/presentation-api.html
+++ b/LayoutTests/presentation/presentation-api.html
@@ -10,8 +10,8 @@ test(function() {
     assert_true('session' in navigator.presentation);
     assert_true('startSession' in navigator.presentation);
     assert_true('joinSession' in navigator.presentation);
-    assert_true('onavailablechange' in navigator.presentation);
     assert_true('ondefaultsessionstart' in navigator.presentation);
+    assert_true('getAvailability' in navigator.presentation);
 }, "Test that the Presentation API is present.")
 
 test(function() {
@@ -19,8 +19,8 @@ test(function() {
   assert_equals(typeof(navigator.presentation.session), "object");
   assert_equals(typeof(navigator.presentation.startSession), "function");
   assert_equals(typeof(navigator.presentation.joinSession), "function");
-  assert_equals(typeof(navigator.presentation.onavailablechange), "object");
   assert_equals(typeof(navigator.presentation.ondefaultsessionstart), "object");
+  assert_equals(typeof(navigator.presentation.getAvailability), "function");
 }, "Test the Presentation API property types.");
 
 test(function() {
@@ -30,4 +30,3 @@ test(function() {
 </script>
 </body>
 </html>
-