Add multi-process notification class.

chrome/common/multi_process_notification.h

+// Copyright (c) 2011 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 CHROME_COMMON_MULTI_PROCESS_NOTIFICATION_H_
+#define CHROME_COMMON_MULTI_PROCESS_NOTIFICATION_H_
+#pragma once
+
+#include <string>
+
+#include "base/scoped_ptr.h"
+#include "base/task.h"
+
+class Task;
+class MessageLoop;
+
+// Platform abstraction for a notification that can be sent between processes.
+// Notifications are strings. The string will be prefixed accordingly per
+// platform (so on MacOSX a "Happy" notification will become

[Mark Mentovai, 2011/01/04 18:19:33]

Mac OS X is generally spelled with three spaces.

[dmac, 2011/01/06 06:06:03]

Done.

+// "org.chromium.Happy").
+namespace multi_process_notification {
+
+class ListenerImpl;
+
+// Posts a notification. Returns true if the notification was posted.
+bool Post(const std::string& name);
+
+// A notification listener. Will listen for a given notification and
+// call the delegate. Note that the delegate is not owned by the listener.
+class Listener {
+ public:
+  class Delegate {
+   public:
+    virtual void OnNotificationReceived(const std::string& name) = 0;

[Mark Mentovai, 2011/01/04 18:19:33]

Wanna declare a virtual destructor?

[dmac, 2011/01/06 06:06:03]

Done.

+  };
+
+  Listener(const std::string& name, Delegate* delegate);
+  virtual ~Listener();
+
+  virtual bool Start();
+
+ private:
+  scoped_ptr<ListenerImpl> impl_;
+};
+
+// A delegate implementation that performs a task when a notification is
+// received. Note that it does not check the notification, and will fire
+// for any notification it receives.
+class PerformTaskOnNotification : public Listener::Delegate {
+  public:

[Mark Mentovai, 2011/01/04 18:19:33]

Bogus indentation throughout this class.

[dmac, 2011/01/06 06:06:03]

Done.

+    explicit PerformTaskOnNotification(Task* task) : task_(task) {

[Mark Mentovai, 2011/01/04 18:19:33]

Should this class really define its implementation in this header? Should there
be a multi_process_notification.cc where the implementation could go? Maybe talk
to erg, who took a lot of code out of headers. I don’t know exactly what his
threshold criteria were, but this may be borderline.

[dmac, 2011/01/06 06:06:03]

Done.

+    }
+
+    virtual void OnNotificationReceived(const std::string& name) {
+      task_->Run();
+      task_.reset();
+    }
+
+    bool notification_called() {
+      return task_.get() == NULL;
+    }
+
+  private:
+    scoped_ptr<Task> task_;
+  };
+
+}  // namespace multi_process_notification
+
+#endif  // CHROME_COMMON_MULTI_PROCESS_NOTIFICATION_H_