Clean up browser tests in Files.app.

chrome/test/data/extensions/api_test/file_manager_browsertest/background.js

Index: chrome/test/data/extensions/api_test/file_manager_browsertest/background.js
diff --git a/chrome/test/data/extensions/api_test/file_manager_browsertest/background.js b/chrome/test/data/extensions/api_test/file_manager_browsertest/background.js
index bc60f6fb58f86668d2c4e8440117945320275a24..375f6cf4c24a8a2361e711f02c1eac821eb24e4a 100644
--- a/chrome/test/data/extensions/api_test/file_manager_browsertest/background.js
+++ b/chrome/test/data/extensions/api_test/file_manager_browsertest/background.js
@@ -28,6 +28,54 @@ function callRemoteTestUtil(func, appId, args, callback) {
       callback);
 }
 
+/**
+ * Executes a sequence of test steps.
+ * @constructor
+ */
+function StepsRunner() {
+  /**
+   * List of steps.
+   * @type {Array.function>}
+   * @private
+   */
+  this.steps_ = [];
+}
+
+/**
+ * Creates a StepsRunner instance and runs the passed steps.
+ */
+StepsRunner.run = function(steps) {
+  var stepsRunner = new StepsRunner();
+  stepsRunner.run_(steps);
+};
+
+StepsRunner.prototype = {
+  /**
+   * @return {function} The next closure.
+   */
+  get next() {
+    return this.steps_.shift();
+  }
+};
+
+/**
+ * Runs a sequence of the added test steps.
+ * @type {Array.<function>} List of the sequential steps.
+ */
+StepsRunner.prototype.run_ = function(steps) {
+  this.steps_ = steps.slice(0);
+
+  // An extra step which acts as an empty callback for optional asynchronous
+  // calls in the last provided step.
+  this.steps_.push(function() {});
+
+  this.steps_ = this.steps_.map(function(f) {
+    return chrome.test.callbackPass(f.bind(this));
+  }.bind(this));
+
+  this.next();
+};
+
 chrome.test.runTests([
   // Waits for the C++ code to send a string identifying a test, then runs that
   // test.