chromeos: Don't spam logs with tlsdate D-Bus errors at boot.

chromeos/dbus/system_clock_client.h

 // Copyright (c) 2013 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 CHROMEOS_DBUS_SYSTEM_CLOCK_CLIENT_H_
 #define CHROMEOS_DBUS_SYSTEM_CLOCK_CLIENT_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "chromeos/chromeos_export.h"
 #include "chromeos/dbus/dbus_client.h"
 
 namespace chromeos {
 
 // SystemClockClient is used to communicate with the system clock.
 class CHROMEOS_EXPORT SystemClockClient : public DBusClient {
  public:
   // Interface for observing changes from the system clock.
   class Observer {
    public:
     // Called when the status is updated.
-    virtual void SystemClockUpdated();
+    virtual void SystemClockUpdated() {}
 
-    // Called when the system clock has become settable or unsettable, e.g.,
+    // Called when the system clock has become settable or unsettable, e.g.
     // when the clock syncs with or goes out of sync with the network.
-    virtual void SystemClockCanSetTimeChanged(bool can_set_time);
+    virtual void SystemClockCanSetTimeChanged(bool can_set_time) {}
 
    protected:
     virtual ~Observer() {}
   };
 
-  ~SystemClockClient() override;
-
   // Adds the given observer.
   virtual void AddObserver(Observer* observer) = 0;
   // Removes the given observer if this object has the observer.
   virtual void RemoveObserver(Observer* observer) = 0;
   // Returns true if this object has the given observer.
   virtual bool HasObserver(const Observer* observer) const = 0;
 
   // Sets the system clock.
   virtual void SetTime(int64_t time_in_seconds) = 0;
 
   // Checks if the system time can be set.
   virtual bool CanSetTime() = 0;
 
   // Creates the instance.
   static SystemClockClient* Create();
 
  protected:
   // Create() should be used instead.
   SystemClockClient();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SystemClockClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_SYSTEM_CLOCK_CLIENT_H_