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

chromeos/dbus/system_clock_client.h

Index: chromeos/dbus/system_clock_client.h
diff --git a/chromeos/dbus/system_clock_client.h b/chromeos/dbus/system_clock_client.h
index 98a48929f30d775ef1c456c6f75552ef769fb5e3..fbfe309846c067081a250bb1e2e210b9e7e1527d 100644
--- a/chromeos/dbus/system_clock_client.h
+++ b/chromeos/dbus/system_clock_client.h
@@ -21,18 +21,16 @@ class CHROMEOS_EXPORT SystemClockClient : public DBusClient {
   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.