Media Galleries API Scanning: Add Scan Permission and basic test.

chrome/test/data/extensions/api_test/media_galleries/no_access/test.js

 // Copyright (c) 2012 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.
 
 var mediaGalleries = chrome.mediaGalleries;
 
 var galleries;
 var testResults = [];
 var expectedFileSystems;
 
@@ skipping 45 matching lines @@
         dirReader.readEntries(mediaFileSystemsDirectoryEntryCallback,
                               mediaFileSystemsDirectoryErrorCallback);
       }
     },
     function validFileCopyToShouldFail() {
       runCopyToTest(validWEBPImageCase, false /* expect failure */);
     },
     function invalidFileCopyToShouldFail() {
       runCopyToTest(invalidWEBPImageCase, false /* expect failure */);
     },
+    function MediaScanWithoutPermission() {
+      var startListener = function(details) {
+        chrome.test.assertEq('error', details.type);
+        mediaGalleries.onScanProgress.removeListener(startListener);
+        chrome.test.succeed();
+      }
+      mediaGalleries.onScanProgress.addListener(startListener);
+
+      mediaGalleries.startMediaScan();
+    }
   ]);
 })