[Sync] Fix flakiness from Sessions refactor

chrome/browser/ui/toolbar/recent_tabs_sub_menu_model_unittest.cc

 // Copyright 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.
 
 #include "chrome/browser/ui/toolbar/recent_tabs_sub_menu_model.h"
 
 #include <memory>
 #include <string>
 #include <vector>
 
@@ skipping 555 matching lines @@
   TestRecentTabsSubMenuModel model(NULL, browser(), GetOpenTabsDelegate());
   int num_items = model.GetItemCount();
   EXPECT_EQ(9, num_items);
 
   std::vector<base::string16> tab_titles =
       recent_tabs_builder.GetTabTitlesSortedByRecency();
   for (int i = 0; i < 4; ++i)
     EXPECT_EQ(tab_titles[i], model.GetLabelAt(i + 5));
 }
 
-// Flaky, see crbug.com/671902.
-TEST_F(RecentTabsSubMenuModelTest, DISABLED_MaxWidth) {
+TEST_F(RecentTabsSubMenuModelTest, MaxWidth) {
   // Create 1 session with 1 window and 1 tab.
   RecentTabsBuilderTestHelper recent_tabs_builder;
   recent_tabs_builder.AddSession();
   recent_tabs_builder.AddWindow(0);
   recent_tabs_builder.AddTab(0, 0);
   RegisterRecentTabs(&recent_tabs_builder);
 
   // Menu index  Menu items
   // ----------------------------------------------------------
   // 0           History
@@ skipping 20 matching lines @@
   // 2           Recently closed heaer (disabled)
   // 3           <separator>
   // 4           No tabs from other Devices
 
   TestRecentTabsSubMenuModel model(NULL, browser(), NULL);
   EXPECT_EQ(5, model.GetItemCount());
   EXPECT_EQ(-1, model.GetMaxWidthForItemAtIndex(2));
   EXPECT_NE(-1, model.GetMaxWidthForItemAtIndex(3));
   EXPECT_EQ(-1, model.GetMaxWidthForItemAtIndex(4));
 }