[filebrowser] Introduce View action for supported file types (e.g. pdf).

chrome/test/data/extensions/api_test/filebrowser_component/write.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.
 
 function readFile(entry, successCallback, errorCallback) {
   var reader = new FileReader();
   reader.onloadend = function(e) {
     successCallback(reader.result);
   };
   reader.onerror = function(e) {
@@ skipping 23 matching lines @@
          error = {message: 'File content not as expected. ' +
                            'Expected: "' + expectedText + '", ' +
                            'Read: ' + text + '".'};
        }
        callback(error);
      },
      callback);
 };
 
 chrome.test.runTests([function tab() {
-  var expectedTasks = {'TextAction': ['filesystem:*.txt'],
+  var expectedTasks = {'AbcAction': ['filesystem:*.abc'],
                        'BaseAction': ['filesystem:*', 'filesystem:*.*']};
   var expectations = new TestExpectations(expectedTasks, verifyFileContent);
 
   var testRunner = new TestRunner(expectations);
   testRunner.runTest();
 }]);