[remoting host] Only watch for material changes to NSS DB files

remoting/host/linux/certificate_watcher.h

 // Copyright 2016 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 REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_
 #define REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_
 
 #include <memory>
 
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 #include "remoting/host/host_status_monitor.h"
 #include "remoting/host/host_status_observer.h"
 
 namespace remoting {
 
+class CertDbContentWatcher;
+
 // This class watches the cert database and notifies the host to restart when
 // a change of the database is detected. The runner script will restart the host
 // when the host is killed then the new host will capture any new changes of the
 // database.
 //
 // Acceptable false positives will be caused by desktop sessions and other
 // external programs.
 //
 // Implements HostStatusObserver to defer restart action when the host is
 // connected to a client.
@@ skipping 19 matching lines @@
 
   // HostStatusObserver interface.
   void OnClientConnected(const std::string& jid) override;
   void OnClientDisconnected(const std::string& jid) override;
 
   // Will only work before the watcher starts.
   void SetDelayForTests(const base::TimeDelta& delay);
   void SetWatchPathForTests(const base::FilePath& watch_path);
 
  private:
+  friend class CertDbContentWatcher;
+
   // Returns true if the watcher has started.
   bool is_started() const;
 
-  // Callback passed to |file_watcher_|. Runs in IO thread.
-  static void OnCertDirectoryChanged(
-      scoped_refptr<base::SingleThreadTaskRunner> network_task_runner,
-      base::WeakPtr<CertificateWatcher> watcher_, const base::FilePath& path,
-      bool error);
-
-  // Runs in the caller's thread.
-  void DirectoryChanged(const base::FilePath& path, bool error);
-
-  // Called by |restart_timer_| when it's time to reset the host.
-  // It will defer restart if |inhibit_restart_scheduled_| flag is set to true.
-  void OnTimer();
+  // Runs in the caller's thread. It will defer restarting the host if
+  // |inhibit_restart_scheduled_| flag is set to true.
+  void DatabaseChanged();
 
   // Reference to the monitor
   base::WeakPtr<HostStatusMonitor> monitor_;
 
   // Called when a restart is scheduled.
   base::Closure restart_action_;
 
   // The runner that runs everything other than the file watcher.
   scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner_;
 
   // The runner that runs the file watcher.
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   bool inhibit_mode_ = false;
 
   bool restart_pending_ = false;
 
   // Path of the certificate files/directories.
   base::FilePath cert_watch_path_;
 
-  // The file watcher to watch changes inside the certificate folder.
-  std::unique_ptr<base::FilePathWatcher> file_watcher_;
+  // The watcher implementation that watches the files on the IO thread.
+  std::unique_ptr<CertDbContentWatcher> content_watcher_;
 
-  // The time to wait to restart when it is scheduled.
+  // The time to wait before re-reading the DB files after a change is
+  // detected.
   base::TimeDelta delay_;
 
-  // Timer to delay the restart action.
-  std::unique_ptr<base::DelayTimer> restart_timer_;
-
   base::WeakPtrFactory<CertificateWatcher> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CertificateWatcher);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_