[AudioPlayer] Add test for opening another file from Files.app

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

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 'use strict';
 
 /**
  * Extension ID of Files.app.
  * @type {string}
  * @const
@@ skipping 97 matching lines @@
       } else {
         return result;
       }
     });
   };
   return step();
 };
 
 /**
  * Waits until a window having the given ID prefix appears.
- * @param {string} appIdPrefix ID prefix of the requested window.
- * @param {Promise} promise Promise to be fulfilled with a found window's ID.
+ * @param {string} windowIdPrefix ID prefix of the requested window.
+ * @return {Promise} promise Promise to be fulfilled with a found window's ID.
  */
 function waitForWindow(windowIdPrefix) {
   return repeatUntil(function() {
     return callRemoteTestUtil('getWindows', null, []).then(function(windows) {
       for (var id in windows) {
         if (id.indexOf(windowIdPrefix) === 0)
           return id;
       }
       return pending('Window with the prefix %s is not found.', windowIdPrefix);
     });
   });
 }
 
 /**
+ * Closes a window and waits until the window is closed.
+ *
+ * @param {string} windowId ID of the window to close.
+ * @return {Promise} promise Promise to be fulfilled with the result (true:
+ *     success, false: failed).
+ */
+function closeWindowAndWait(windowId) {
+  // Closes the window.
+  return callRemoteTestUtil('closeWindow', null, [windowId]).then(
+      function(result) {
+        // Returns false when the closing is failed.
+        if (!result)
+          return false;
+
+        return repeatUntil(function() {
+          return callRemoteTestUtil('getWindows', null, []).then(
+              function(windows) {
+                for (var id in windows) {
+                  if (id === windowId) {
+                    // Window is still available. Continues waiting.
+                    return pending('Window with the prefix %s is not found.',
+                                   windowId);
+                  }
+                }
+                // Window is not available. Closing is done successfully.
+                return true;
+              }
+          );
+        });
+      }
+  );
+}
+
+/**
  * Waits until the window turns to the given size.
  * @param {string} windowId Target window ID.
  * @param {number} width Requested width in pixels.
  * @param {number} height Requested height in pixels.
  */
 function waitForWindowGeometry(windowId, width, height) {
   return repeatUntil(function() {
     return callRemoteTestUtil('getWindows', null, []).then(function(windows) {
       if (!windows[windowId])
         return pending('Window %s is not found.', windowId);
@@ skipping 587 matching lines @@
         chrome.test.runTests([function() {
           chrome.test.fail(testCaseName + ' is not found.');
         }]);
         return;
       }
       chrome.test.runTests([testcase[testCaseName]]);
     }
   ];
   steps.shift()();
 });