[Sync] Introduce SyncedSessionWindow type.

components/sync_sessions/revisit/sessions_page_revisit_observer.cc

 // Copyright 2015 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_sessions/revisit/sessions_page_revisit_observer.h"
 
 #include <utility>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 39 matching lines @@
   // to make things a little bit messier, we only have an accurate modified time
   // for the tabs/current entries. So use index offset for forward/back entries.
   PageEquality page_equality(url);
   CurrentTabMatcher current_matcher(page_equality);
   OffsetTabMatcher offset_matcher(page_equality);
 
   std::vector<const SyncedSession*> foreign_sessions;
   if (provider_->GetAllForeignSessions(&foreign_sessions)) {
     for (const SyncedSession* session : foreign_sessions) {
       for (const auto& key_value : session->windows) {
-        for (const auto& tab : key_value.second->tabs) {
+        for (const auto& tab : key_value.second->wrapped_window.tabs) {
           // These matchers look identical and could easily implement an
           // interface and we could iterate through a vector of matchers here.
           // However this would cause quite a bit of overhead at the inner most
           // loop of something that takes linear time in relation to the number
           // of open foreign tabs. A small fraction of users have thousands of
           // open tabs.
           current_matcher.Check(tab.get());
           offset_matcher.Check(tab.get());
         }
       }
     }
   }
 
   // emit even if there are no foreign sessions so that that counts all match.
   current_matcher.Emit(transition);
   offset_matcher.Emit(transition);
 
   base::TimeDelta duration(base::TimeTicks::Now() - start);
   UMA_HISTOGRAM_TIMES("Sync.PageRevisitSessionDuration", duration);
 }
 
 }  // namespace sync_sessions