Password manager internals page service: introduction

components/password_manager/core/browser/log_router.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_PASSWORD_MANAGER_CORE_BROWSER_LOG_ROUTER_H_
+#define COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_LOG_ROUTER_H_
+
+#include <set>
+#include <string>
+
+#include "base/macros.h"
+#include "base/observer_list.h"
+
+namespace password_manager {
+
+class PasswordManagerClient;
+class PasswordManagerLogger;
+
+// The router stands between PasswordManagerClient instances and log receivers.
+// During the process of saving a password, the password manager code generates
+// the log strings, and passes them to the router. The router distributes the
+// logs to the receivers for displaying.
+//
+// TODO(vabr): The receivers are objects of type PasswordManagerLogger. That
+// type should be renamed to LogReceiver instead.
+class LogRouter {
+ public:
+  LogRouter();
+  virtual ~LogRouter();
+
+  // Passes logs to the router. Only call when there are receivers registered.
+  void ProcessLog(const std::string& text);
+
+  // All four (Unr|R)egister* methods below are safe to call from the
+  // constructor of the registered object, because they do not call that object,
+  // and the router only runs on a single thread.
+
+  // The clients must register to be notified about whether there are some
+  // receivers or not. RegisterClient adds |client| to the right observer list
+  // and returns true iff there are some receivers registered.
+  bool RegisterClient(PasswordManagerClient* client);
+  // Remove |client| from the observers list.
+  void UnregisterClient(PasswordManagerClient* client);
+
+  // The receivers must register to get updates with new logs in the future.
+  // RegisterReceiver adds |receiver| to the right observer list, and returns
+  // the logs accumulated so far. (It returns by value, not const ref, to
+  // provide a snapshot as opposed to a link to |accumulated_logs_|.)
+  std::string RegisterReceiver(PasswordManagerLogger* receiver);
+  // Remove |receiver| from the observers list.
+  void UnregisterReceiver(PasswordManagerLogger* receiver);
+
+ private:
+  // Observer lists for clients and receivers. The |true| in the template
+  // specialisation means that they will check that all observers were removed
+  // on destruction.
+  ObserverList<PasswordManagerClient, true> clients_;
+  ObserverList<PasswordManagerLogger, true> receivers_;
+
+  // Logs accumulated since the first receiver was registered.
+  std::string accumulated_logs_;
+
+  DISALLOW_COPY_AND_ASSIGN(LogRouter);
+};
+
+}  // namespace password_manager
+
+#endif  // COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_LOG_ROUTER_H_