Hook up system clock update dbus signal to chrome and ash tray ui.

chromeos/dbus/system_clock_client.cc

+// 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.
+
+#include "chromeos/dbus/system_clock_client.h"
+
+#include "base/bind.h"
+#include "dbus/bus.h"
+#include "dbus/message.h"
+#include "dbus/object_path.h"
+#include "dbus/object_proxy.h"
+#include "third_party/cros_system_api/dbus/service_constants.h"
+
+namespace chromeos {
+
+// The SystemClockClient implementation used in production.
+class SystemClockClientImpl : public SystemClockClient {
+ public:
+  explicit SystemClockClientImpl(dbus::Bus* bus)
+      : system_clock_proxy_(NULL),
+        weak_ptr_factory_(this) {
+    system_clock_proxy_ = bus->GetObjectProxy(
+        system_clock::kSystemClockServiceName,
+        dbus::ObjectPath(system_clock::kSystemClockServicePath));
+
+    // Monitor the D-Bus signal for TimeUpdated changes.
+    system_clock_proxy_->ConnectToSignal(
+        system_clock::kSystemClockInterface,
+        system_clock::kSystemClockUpdated,
+        base::Bind(&SystemClockClientImpl::TimeUpdatedReceived,
+                   weak_ptr_factory_.GetWeakPtr()),
+        base::Bind(&SystemClockClientImpl::TimeUpdatedConnected,
+                   weak_ptr_factory_.GetWeakPtr()));
+  }
+
+  virtual ~SystemClockClientImpl() {
+  }
+
+  // SystemClockClient overrides:
+  virtual void AddObserver(Observer* observer) OVERRIDE {
+    observers_.AddObserver(observer);
+  }
+
+  virtual void RemoveObserver(Observer* observer) OVERRIDE {
+    observers_.RemoveObserver(observer);
+  }
+
+  virtual bool HasObserver(Observer* observer) OVERRIDE {
+    return observers_.HasObserver(observer);
+  }
+
+ private:
+  // Called when a TimeUpdated signal is received.
+  void TimeUpdatedReceived(dbus::Signal* signal) {
+    VLOG(1) << "TimeUpdated signal received: " << signal->ToString();

[Dan Beam, 2016/11/28 21:42:50]

is |signal| guaranteed to be non-null here?

[stevenjb, 2016/11/28 21:58:32]

Yes. ObjectProxy::HandleMessage calls RunMethod with a constructed signal.

+    dbus::MessageReader reader(signal);
+    FOR_EACH_OBSERVER(Observer, observers_, SystemClockUpdated());
+  }
+
+  // Called when the TimeUpdated signal is initially connected.
+  void TimeUpdatedConnected(const std::string& interface_name,
+                            const std::string& signal_name,
+                            bool success) {
+    LOG_IF(ERROR, !success)
+        << "Failed to connect to TimeUpdated signal.";
+  }
+
+  dbus::ObjectProxy* system_clock_proxy_;
+  ObserverList<Observer> observers_;
+
+  // Note: This should remain the last member so it'll be destroyed and
+  // invalidate its weak pointers before any other members are destroyed.
+  base::WeakPtrFactory<SystemClockClientImpl> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(SystemClockClientImpl);
+};
+
+// The SystemClockClient implementation used on Linux desktop,
+// which does nothing.
+class SystemClockClientStubImpl : public SystemClockClient {
+ public:
+  SystemClockClientStubImpl() {}
+  ~SystemClockClientStubImpl() {}
+
+  // SystemClockClient overrides:
+  virtual void AddObserver(Observer* observer) OVERRIDE {}
+  virtual void RemoveObserver(Observer* observer) OVERRIDE {}
+  virtual bool HasObserver(Observer* observer) OVERRIDE { return false; }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SystemClockClientStubImpl);
+};
+
+SystemClockClient::SystemClockClient() {
+}
+
+SystemClockClient::~SystemClockClient() {
+}
+
+// static
+SystemClockClient* SystemClockClient::Create(
+    DBusClientImplementationType type,
+    dbus::Bus* bus) {
+  if (type == REAL_DBUS_CLIENT_IMPLEMENTATION) {
+    return new SystemClockClientImpl(bus);
+  }
+  DCHECK_EQ(STUB_DBUS_CLIENT_IMPLEMENTATION, type);
+  return new SystemClockClientStubImpl();
+}
+
+}  // namespace chromeos