Add permissions helper class to carry out promise based testing

LayoutTests/resources/permissions-helper.js

Index: LayoutTests/resources/permissions-helper.js
diff --git a/LayoutTests/resources/permissions-helper.js b/LayoutTests/resources/permissions-helper.js
new file mode 100644
index 0000000000000000000000000000000000000000..2f8bda3a6482972077e081a7aebb294168be8c6f
--- /dev/null
+++ b/LayoutTests/resources/permissions-helper.js
@@ -0,0 +1,36 @@
+function permissionNameToPermissionObject(permissionName) {

[mlamouri (slow - plz ping), 2015/08/21 17:15:23]

It would be good if we could make sure this is not accessible from outside this
file.

I'm not a JS expert but what about doing:

var PermissionsHelper = (function() {
  function permissionNameToObject(name) {
    [...]
  }

  return {
    setPermission: function() {
      [...] // alternatively, you have it define above and you just use the
internal one here.
    }
  }
});

I think that will make PermissionsHelper.setPermission() available from script
include this file.

[Lalit Maganti, 2015/08/21 18:30:19]

Done.

+  switch (permissionName) {
+    case "midi":
+      return {name: "midi"}
+    case "midi-sysex":
+      return {name: "midi", sysex: true}
+    case "push-messaging":
+      return {name: "push", userVisibleOnly: true}
+    case "notifications":
+      return {name: "midi"}

[mlamouri (slow - plz ping), 2015/08/21 17:15:23]

midi?

[Lalit Maganti, 2015/08/21 18:30:19]

Done.

+    case "geolocation":
+      return {name: "geolocation", sysex: true}

[mlamouri (slow - plz ping), 2015/08/21 17:15:23]

sysex?

[Lalit Maganti, 2015/08/21 18:30:19]

Done.

+    case "protected-media-identifier":
+    default:
+      // We can't deal with these two yet.

[mlamouri (slow - plz ping), 2015/08/21 17:15:23]

These 'two'?

[Lalit Maganti, 2015/08/21 18:30:19]

Done.

+      return {name: "midi"}

[mlamouri (slow - plz ping), 2015/08/21 17:15:23]

Can you actually throw in that case?

[Lalit Maganti, 2015/08/21 18:30:19]

Done.

+  }
+}
+
+function setPermission(testRunner, permissionName, newState) {

[mlamouri (slow - plz ping), 2015/08/21 17:15:23]

Can we use testRunner directly instead of taking it? We should be in the same
scope, right?

nit: s/newState/state/
nit: s/permissionName/name/

[Lalit Maganti, 2015/08/21 18:30:19]

Done.

+  return new Promise(function(resolver, reject) {
+    navigator.permissions.query(permissionNameToPermissionObject(permissionName)).then(function(result) {
+        if (result.state == newState) {
+            resolver()
+            return;
+        }
+
+        result.onchange = function() {
+            result.onchange = null;
+            resolver();
+        };
+
+        testRunner.setPermission(permissionName, newState, location.origin, location.origin);
+    });
+  });
+}