1 files changed, 52 insertions, 0 deletions
diff --git a/toolkit/components/aboutperformance/tests/browser/head.js b/toolkit/components/aboutperformance/tests/browser/head.js
new file mode 100644
index 0000000000..a15536ffd3
--- /dev/null
+++ b/toolkit/components/aboutperformance/tests/browser/head.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+var { utils: Cu, interfaces: Ci, classes: Cc } = Components;
+
+Cu.import("resource://gre/modules/Services.jsm", this);
+
+function promiseContentResponse(browser, name, message) {
+  let mm = browser.messageManager;
+  let promise = new Promise(resolve => {
+    function removeListener() {
+      mm.removeMessageListener(name, listener);
+    }
+
+    function listener(msg) {
+      removeListener();
+      resolve(msg.data);
+    }
+
+    mm.addMessageListener(name, listener);
+    registerCleanupFunction(removeListener);
+  });
+  mm.sendAsyncMessage(name, message);
+  return promise;
+}
+function promiseContentResponseOrNull(browser, name, message) {
+  if (!browser.messageManager) {
+    return null;
+  }
+  return promiseContentResponse(browser, name, message);
+}
+
+/**
+ * `true` if we are running an OS in which the OS performance
+ * clock has a low precision and might unpredictably
+ * never be updated during the execution of the test.
+ */
+function hasLowPrecision() {
+  let [sysName, sysVersion] = [Services.sysinfo.getPropertyAsAString("name"), Services.sysinfo.getPropertyAsDouble("version")];
+  info(`Running ${sysName} version ${sysVersion}`);
+
+  if (sysName == "Windows_NT" && sysVersion < 6) {
+    info("Running old Windows, need to deactivate tests due to bad precision.");
+    return true;
+  }
+  if (sysName == "Linux" && sysVersion <= 2.6) {
+    info("Running old Linux, need to deactivate tests due to bad precision.");
+    return true;
+  }
+  info("This platform has good precision.")
+  return false;
+}