Revert of [sync] Replace FakeServer's implementation with LoopbackServer invocations.

components/sync/engine_impl/loopback_server/loopback_server.h

Index: components/sync/engine_impl/loopback_server/loopback_server.h
diff --git a/components/sync/engine_impl/loopback_server/loopback_server.h b/components/sync/engine_impl/loopback_server/loopback_server.h
index d9fac61c1fca92c69fe6dfea69a0766e5bc97809..a69c99e4ac7c7da84751a21b88d3da0642352830 100644
--- a/components/sync/engine_impl/loopback_server/loopback_server.h
+++ b/components/sync/engine_impl/loopback_server/loopback_server.h
@@ -22,25 +22,11 @@
 #include "components/sync/protocol/loopback_server.pb.h"
 #include "components/sync/protocol/sync.pb.h"
 
-namespace fake_server {
-class FakeServer;
-}
-
 namespace syncer {
 
 // A loopback version of the Sync server used for local profile serialization.
 class LoopbackServer {
  public:
-  class ObserverForTests {
-   public:
-    virtual ~ObserverForTests() {}
-
-    // Called after the server has processed a successful commit. The types
-    // updated as part of the commit are passed in |committed_model_types|.
-    virtual void OnCommit(const std::string& committer_id,
-                          syncer::ModelTypeSet committed_model_types) = 0;
-  };
-
   explicit LoopbackServer(const base::FilePath& persistent_file);
   virtual ~LoopbackServer();
 
@@ -54,9 +40,6 @@
                      std::string* response);
 
  private:
-  // Allow the FakeServer decorator to inspect the internals of this class.
-  friend class fake_server::FakeServer;
-
   using EntityMap =
       std::map<std::string, std::unique_ptr<LoopbackServerEntity>>;
 
@@ -119,35 +102,6 @@
   // Returns the store birthday.
   std::string GetStoreBirthday() const;
 
-  // Returns all entities stored by the server of the given |model_type|.
-  // This method is only used in tests.
-  std::vector<sync_pb::SyncEntity> GetSyncEntitiesByModelType(
-      syncer::ModelType model_type);
-
-  // Creates a DicionaryValue representation of all entities present in the
-  // server. The dictionary keys are the strings generated by ModelTypeToString
-  // and the values are ListValues containing StringValue versions of entity
-  // names. Used by test to verify the contents of the server state.
-  std::unique_ptr<base::DictionaryValue> GetEntitiesAsDictionaryValue();
-
-  // Modifies the entity on the server with the given |id|. The entity's
-  // EntitySpecifics are replaced with |updated_specifics| and its version is
-  // updated to n+1. If the given |id| does not exist or the ModelType of
-  // |updated_specifics| does not match the entity, false is returned.
-  // Otherwise, true is returned to represent a successful modification.
-  //
-  // This method sometimes updates entity data beyond EntitySpecifics. For
-  // example, in the case of a bookmark, changing the BookmarkSpecifics title
-  // field will modify the top-level entity's name field.
-  // This method is only used in tests.
-  bool ModifyEntitySpecifics(const std::string& id,
-                             const sync_pb::EntitySpecifics& updated_specifics);
-
-  // This method is only used in tests.
-  bool ModifyBookmarkEntity(const std::string& id,
-                            const std::string& parent_id,
-                            const sync_pb::EntitySpecifics& updated_specifics);
-
   // Serializes the server state to |proto|.
   void SerializeState(sync_pb::LoopbackServerProto* proto) const;
 
@@ -159,10 +113,6 @@
 
   // Loads all entities and server state from a protobuf file in |filename|.
   bool LoadStateFromFile(const base::FilePath& filename);
-
-  void set_observer_for_tests(ObserverForTests* observer) {
-    observer_for_tests_ = observer;
-  }
 
   // This is the last version number assigned to an entity. The next entity will
   // have a version number of version_ + 1.
@@ -178,9 +128,6 @@
 
   // Used to verify that LoopbackServer is only used from one thread.
   base::ThreadChecker thread_checker_;
-
-  // Used to observe the completion of commit messages for the sake of testing.
-  ObserverForTests* observer_for_tests_;
 };
 
 }  // namespace syncer