[Sync] Added integ tests to verify UserEvents retry on TRANSIENT_ERROR.

components/sync/test/fake_server/fake_server.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_TEST_FAKE_SERVER_FAKE_SERVER_H_
 #define COMPONENTS_SYNC_TEST_FAKE_SERVER_FAKE_SERVER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 128 matching lines @@
   // Forces every request to fail in a way that simulates a network failure.
   // This can be used to trigger exponential backoff in the client.
   void DisableNetwork();
 
   // Returns the entity ID of the Bookmark Bar folder.
   std::string GetBookmarkBarFolderId() const;
 
   // Returns the current FakeServer as a WeakPtr.
   base::WeakPtr<FakeServer> AsWeakPtr();
 
+  using ResponseTypeProvider =
+      base::RepeatingCallback<sync_pb::CommitResponse::ResponseType(
+          const FakeServerEntity& entity)>;
+
+  // Use this callback to generate response types for entities. They will still
+  // be "committed" and stored as normal, this only affects the response type
+  // the client sees. This allows tests to still inspect what the client has
+  // done, although not as useful of a mechanism for multi client tests. Care
+  // should be taken when failing responses, as the client will go into
+  // exponential backoff, which can cause tests to be slow or time out.
+  void OverrideResponseType(ResponseTypeProvider response_type_override);
+
  private:
   using EntityMap = std::map<std::string, std::unique_ptr<FakeServerEntity>>;
 
   // Gets FakeServer ready for syncing.
   void Init();
 
   // Processes a GetUpdates call.
   bool HandleGetUpdatesRequest(const sync_pb::GetUpdatesMessage& get_updates,
                                sync_pb::GetUpdatesResponse* response);
 
@@ skipping 89 matching lines @@
   base::ObserverList<Observer, true> observers_;
 
   // When true, the server operates normally. When false, a failure is returned
   // on every request. This is used to simulate a network failure on the client.
   bool network_enabled_;
 
   // The last received client to server messages.
   sync_pb::ClientToServerMessage last_commit_message_;
   sync_pb::ClientToServerMessage last_getupdates_message_;
 
+  ResponseTypeProvider response_type_override_;
+
   // Used to verify that FakeServer is only used from one thread.
   base::ThreadChecker thread_checker_;
 
   // Creates WeakPtr versions of the current FakeServer. This must be the last
   // data member!
   base::WeakPtrFactory<FakeServer> weak_ptr_factory_;
 };
 
 }  // namespace fake_server
 
 #endif  // COMPONENTS_SYNC_TEST_FAKE_SERVER_FAKE_SERVER_H_