reland of [sync] Add Sessions integration tests

components/sync/test/fake_server/sessions_hierarchy.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_TEST_FAKE_SERVER_SESSIONS_HIERARCHY_H_
 #define COMPONENTS_SYNC_TEST_FAKE_SERVER_SESSIONS_HIERARCHY_H_
 
 #include <set>
 #include <string>
 
 #include "base/macros.h"
 
 namespace fake_server {
 
 class SessionsHierarchy;
 
 // A representation of the Sync Sessions hierarchy (windows and the URLs of
 // their tabs).
 class SessionsHierarchy {
  public:
   // Creates an empty (no windows) SessionsHierachy.
   SessionsHierarchy();
 
+  // Copy constructor.
+  SessionsHierarchy(const SessionsHierarchy& other);
+
+  // Creates a SessionsHierarchy with specified set of windows.
+  SessionsHierarchy(std::initializer_list<std::multiset<std::string>> windows);
+
   ~SessionsHierarchy();
 
   // Add a window to the builder with one tab.
   void AddWindow(const std::string& tab);
 
   // Add a window to the builder with multiple tabs.
   void AddWindow(const std::multiset<std::string>& tabs);
 
   // Creates and returns a human-readable string version of this object's data.
   std::string ToString() const;
@@ skipping 19 matching lines @@
   // sessions hierarchy).
   using WindowContainer = std::multiset<Window>;
 
   // The windows of the sessions hierarchy.
   WindowContainer windows_;
 };
 
 }  // namespace fake_server
 
 #endif  // COMPONENTS_SYNC_TEST_FAKE_SERVER_SESSIONS_HIERARCHY_H_