downloads: add "No downloads" and "No search results" messages.

chrome/browser/ui/webui/downloads_ui_browsertest.js

 // Copyright 2013 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.
 
 GEN_INCLUDE(['downloads_ui_browsertest_base.js']);
 GEN('#include "chrome/browser/ui/webui/downloads_ui_browsertest.h"');
 
 // Test UI when removing entries is allowed.
 TEST_F('BaseDownloadsWebUITest', 'DeleteAllowed', function() {
   this.testHelper(true, false);
   // TODO(pamg): Mock out the back-end calls, so we can also test removing a
   // single item.
   testDone();
 });
 
+TEST_F('BaseDownloadsWebUITest', 'NoResultsHiddenWhenDownloads', function() {
+  assertNotEquals(0, downloads.size());
+  expectFalse($('downloads-display').hidden);
+  expectTrue($('no-downloads-or-results').hidden);
+});
+
+/**
+ * @constructor
+ * @extends {BaseDownloadsWebUITest}
+ */
+function EmptyDownloadsWebUITest() {}
+
+EmptyDownloadsWebUITest.prototype = {
+  __proto__: BaseDownloadsWebUITest.prototype,
+
+  /** @override */
+  setUp: function() {
+    // Doesn't create any fake downloads.
+    assertEquals(0, downloads.size());
+  },
+};
+
+TEST_F('EmptyDownloadsWebUITest', 'NoDownloadsMessageShowing', function() {
+  expectTrue($('downloads-display').hidden);
+  expectFalse($('no-downloads-or-results').hidden);
+});
+
 /**
  * Fixture for Downloads WebUI testing when deletions are prohibited.
  * @extends {BaseDownloadsWebUITest}
  * @constructor
  */
 function DownloadsWebUIDeleteProhibitedTest() {}
 
 DownloadsWebUIDeleteProhibitedTest.prototype = {
   __proto__: BaseDownloadsWebUITest.prototype,
 
   /** @override */
   testGenPreamble: function() {
     GEN('  SetDeleteAllowed(false);');
   },
 };
 
 // Test UI when removing entries is prohibited.
 TEST_F('DownloadsWebUIDeleteProhibitedTest', 'DeleteProhibited', function() {
   this.testHelper(false, false);
   // TODO(pamg): Mock out the back-end calls, so we can also test removing a
   // single item.
   testDone();
 });