Bug 711692 - Intermittent service callback log failure fix. r=rstrong.

toolkit/mozapps/update/test/unit/head_update.js.in

@@ -645,12 +645,12 @@ function runUpdateUsingService(aInitialStatus, aExpectedStatus,
     updater.copyTo(applyToUpdater, UPDATER_BIN_FILE);
   }
 
-  // We can't get sync behavior here since Firefox does not wait for the
-  // process launched through the service to finish.  Since the service
-  // launches the updater in the background, providing an observer argument
-  // doesn't solve anything either, so we will rely on watching the
-  // update.status file instead.
-  process.runAsync(args, args.length);
+  // Firefox does not wait for the service command to finish, but
+  // we still launch the process sync to avoid intemittent failures with
+  // the log file not being written out yet.
+  // We will rely on watching the update.status file and waiting for the service
+  // to stop to know the service command is done.
+  process.run(true, args, args.length);
 
   resetEnvironment();
 
@@ -1165,6 +1165,16 @@ function checkCallbackServiceLog() {
   let logFile = AUS_Cc["@mozilla.org/file/local;1"].createInstance(AUS_Ci.nsILocalFile);
   logFile.initWithPath(gServiceLaunchedCallbackLog);
   let logContents = readFile(logFile);
+ 
+  // It is possible for the log file contents check to occur before the log file
+  // contents are completely written so wait until the contents are the expected
+  // value. If the contents are never the expected value then the test will
+  // fail by timing out.
+  if (logContents != expectedLogContents) {
+    logTestInfo("callback service log not expected value, waiting longer");
+    do_timeout(TEST_HELPER_TIMEOUT, checkCallbackServiceLog);
+    return;
+  }
 
   logTestInfo("testing that the callback application successfully launched " +
               "and the expected command line arguments passed to it");