Linux: Refactor udev device monitoring code into its own class so it can be reused more easily.

content/browser/udev_linux.h

+// Copyright (c) 2012 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 CONTENT_BROWSER_UDEV_LINUX_H_
+#define CONTENT_BROWSER_UDEV_LINUX_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/message_pump_libevent.h"
+
+extern "C" {
+struct udev;
+struct udev_device;
+struct udev_monitor;
+}
+

[Lei Zhang, 2012/07/26 01:44:31]

I probably need to add a description here and an example use case... but you can
start reviewing without that.

+namespace content {
+
+class UdevLinux : public base::MessagePumpLibevent::Watcher {
+ public:
+  UdevLinux();
+  virtual ~UdevLinux();
+
+  virtual void Notify(udev_device* device) = 0;

[jam, 2012/07/26 02:11:33]

Instead of implementation inheritance, can you make the constructor of this
class take a callback? then users of this class can use composition instead,
which makes things easier to read.
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Inheri...

+
+ protected:
+  virtual void StartMonitoring();
+  udev* udev_handle();
+  udev_monitor* monitor();
+
+ private:
+  // base::MessagePump:Libevent::Watcher:
+  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
+  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
+
+  // libudev-related items, the main context, and the monitoring context to be
+  // notified about changes to device states.
+  udev* udev_;
+  udev_monitor* monitor_;
+  int monitor_fd_;
+  base::MessagePumpLibevent::FileDescriptorWatcher monitor_watcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(UdevLinux);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_UDEV_LINUX_H_