1 files changed, 66 insertions, 0 deletions
diff --git a/devtools/client/performance/legacy/compatibility.js b/devtools/client/performance/legacy/compatibility.js
new file mode 100644
index 000000000..0c67800d0
--- /dev/null
+++ b/devtools/client/performance/legacy/compatibility.js
@@ -0,0 +1,66 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+const EventEmitter = require("devtools/shared/event-emitter");
+
+/**
+ * A dummy front decorated with the provided methods.
+ *
+ * @param array blueprint
+ *        A list of [funcName, retVal] describing the class.
+ */
+function MockFront(blueprint) {
+  EventEmitter.decorate(this);
+
+  for (let [funcName, retVal] of blueprint) {
+    this[funcName] = (x => typeof x === "function" ? x() : x).bind(this, retVal);
+  }
+}
+
+function MockTimelineFront() {
+  MockFront.call(this, [
+    ["destroy"],
+    ["start", 0],
+    ["stop", 0],
+  ]);
+}
+
+/**
+ * Takes a TabTarget, and checks existence of a TimelineActor on
+ * the server, or if TEST_MOCK_TIMELINE_ACTOR is to be used.
+ *
+ * @param {TabTarget} target
+ * @return {Boolean}
+ */
+function timelineActorSupported(target) {
+  // This `target` property is used only in tests to test
+  // instances where the timeline actor is not available.
+  if (target.TEST_MOCK_TIMELINE_ACTOR) {
+    return false;
+  }
+
+  return target.hasActor("timeline");
+}
+
+/**
+ * Returns a function to be used as a method on an "Front" in ./actors.
+ * Calls the underlying actor's method.
+ */
+function callFrontMethod(method) {
+  return function () {
+    // If there's no target or client on this actor facade,
+    // abort silently -- this occurs in tests when polling occurs
+    // after the test ends, when tests do not wait for toolbox destruction
+    // (which will destroy the actor facade, turning off the polling).
+    if (!this._target || !this._target.client) {
+      return undefined;
+    }
+    return this._front[method].apply(this._front, arguments);
+  };
+}
+
+exports.MockTimelineFront = MockTimelineFront;
+exports.timelineActorSupported = timelineActorSupported;
+exports.callFrontMethod = callFrontMethod;