[Sync] Try to fix race conditions in CookieJarMismatch.

components/sync/test/fake_server/fake_server_verifier.cc

 // Copyright 2014 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 "components/sync/test/fake_server/fake_server_verifier.h"
 
 #include <map>
 #include <memory>
 #include <set>
 #include <vector>
@@ skipping 129 matching lines @@
     // Ensure that all session tags match the first entity. Only one session is
     // supported for verification at this time.
     if (it == sessions.begin())
       session_tag = session_specifics.session_tag();
     else if (session_specifics.session_tag() != session_tag)
       return AssertionFailure() << "Multiple session tags found.";
 
     if (session_specifics.has_header()) {
       session_header = session_specifics.header();
     } else if (session_specifics.has_tab()) {
-      sync_pb::SessionTab tab = session_specifics.tab();
-      tab_ids_to_window_ids[tab.tab_id()] = tab.window_id();
-      tab_ids_to_urls[tab.tab_id()] =
-          tab.navigation(tab.current_navigation_index()).virtual_url();
+      const sync_pb::SessionTab& tab = session_specifics.tab();
+      const sync_pb::TabNavigation& nav =
+          tab.navigation(tab.current_navigation_index());
+      // Only read from tabs that have a title on their current navigation
+      // entry. This the result of an oddity around the timing of sessions
+      // related changes. Sometimes when opening a new window, the first
+      // navigation will be committed before the title has been set. Then a
+      // subsequent commit will go through for that same navigation. Because
+      // this logic is used to ensure synchronization, we are going to exclude
+      // partially omitted navigations. The full navigation should typically be
+      // committed in full immediately after we fail a check because of this.
+      if (nav.has_title()) {
+        tab_ids_to_window_ids[tab.tab_id()] = tab.window_id();
+        tab_ids_to_urls[tab.tab_id()] = nav.virtual_url();
+      }
     }
   }
 
   // Create a SessionsHierarchy from the cached SyncEntity data. This loop over
   // the SessionHeader also ensures its data corresponds to the data stored in
   // each SessionTab.
   SessionsHierarchy actual_sessions;
   ::google::protobuf::RepeatedPtrField<sync_pb::SessionWindow>::const_iterator
       window_it;
   for (window_it = session_header.window().begin();
        window_it != session_header.window().end(); ++window_it) {
     sync_pb::SessionWindow window = *window_it;
     std::multiset<std::string> tab_urls;
     ::google::protobuf::RepeatedField<int>::const_iterator tab_it;
     for (tab_it = window.tab().begin(); tab_it != window.tab().end();
          ++tab_it) {
       int tab_id = *tab_it;
       if (tab_ids_to_window_ids.find(tab_id) == tab_ids_to_window_ids.end()) {
         return AssertionFailure() << "Malformed data: Tab entity not found.";
       }
       tab_urls.insert(tab_ids_to_urls[tab_id]);
     }
     actual_sessions.AddWindow(tab_urls);
   }
   return VerifySessionsHierarchyEquality(expected_sessions, actual_sessions);
 }
 
 }  // namespace fake_server