MD History: truncate title to 300 chars in C++ instead of JS

chrome/test/data/webui/md_history/history_item_test.js

 // Copyright 2016 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.
 
 cr.define('md_history.history_item_test', function() {
   function registerTests() {
     suite('history-item', function() {
       var element;
       var TEST_HISTORY_RESULTS;
       var SEARCH_HISTORY_RESULTS;
@@ skipping 79 matching lines @@
           MockInteractions.tap(items[1].$$('#bookmark-star'));
 
           // Check that focus is shifted to overflow menu icon.
           assertEquals(items[1].root.activeElement, items[1].$['menu-button']);
           // Check that all items matching this url are unstarred.
           assertEquals(element.historyData_[1].starred, false);
           assertEquals(element.historyData_[5].starred, false);
         });
       });
 
-      test('long titles are trimmed', function() {
-        var item = document.createElement('history-item');
-        var longtitle = '0123456789'.repeat(100);
-        item.item =
-            createHistoryEntry('2016-06-30', 'http://example.com/' + longtitle);
-
-        var label = item.$$('history-searched-label');
-        assertEquals(TITLE_MAX_LENGTH, label.title.length);
-      });
-
       teardown(function() {
         element.historyData_ = [];
         element.searchedTerm = '';
       });
     });
   }
   return {
     registerTests: registerTests
   };
 });