Add DeviceMonitorLinux in BrowserMainLoop.

content/browser/device_monitor_linux.cc

+// 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.
+
+// libudev is used for monitoring device changes.
+
+#include "content/browser/device_monitor_linux.h"
+
+#include <libudev.h>
+
+#include <string>
+
+#include "base/system_monitor/system_monitor.h"
+#include "content/browser/udev_linux.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace {
+
+struct SubsystemMap {
+  base::SystemMonitor::DeviceType device_type;
+  const char* subsystem;
+  const char* devtype;
+};
+
+const char kAudioSubsystem[] = "sound";
+const char kVideoSubsystem[] = "video4linux";
+
+// Add more subsystems here for monitoring.
+const SubsystemMap kSubsystemMap[] = {
+  { base::SystemMonitor::DEVTYPE_AUDIO_CAPTURE, kAudioSubsystem, NULL },
+  { base::SystemMonitor::DEVTYPE_VIDEO_CAPTURE, kVideoSubsystem, NULL },
+};
+
+}  // namespace
+
+namespace content {
+
+DeviceMonitorLinux::DeviceMonitorLinux()
+    : io_loop_(NULL) {
+  DCHECK(BrowserThread::IsMessageLoopValid(BrowserThread::IO));
+  BrowserThread::PostTask(BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&DeviceMonitorLinux::Initialize, base::Unretained(this)));
+}
+
+DeviceMonitorLinux::~DeviceMonitorLinux() {
+  DCHECK(!io_loop_);
+}
+
+void DeviceMonitorLinux::Initialize() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // We want to be notified of IO message loop destruction to delete |udev_|.
+  io_loop_ = MessageLoop::current();
+  io_loop_->AddDestructionObserver(this);
+
+  std::vector<UdevLinux::UdevMonitorFilter> filters;
+  for (size_t i = 0; i < arraysize(kSubsystemMap); ++i) {
+    filters.push_back(content::UdevLinux::UdevMonitorFilter(
+        kSubsystemMap[i].subsystem, kSubsystemMap[i].devtype));
+  }
+  udev_.reset(new UdevLinux(filters,
+      base::Bind(&DeviceMonitorLinux::OnDevicesChanged,
+                 base::Unretained(this))));
+}
+
+void DeviceMonitorLinux::WillDestroyCurrentMessageLoop() {
+  DCHECK_EQ(MessageLoop::current(), io_loop_);
+
+  udev_.reset();
+  io_loop_ = NULL;
+}
+
+void DeviceMonitorLinux::OnDevicesChanged(udev_device* device) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(device);
+
+  base::SystemMonitor::DeviceType device_type =

[Lei Zhang, 2012/07/31 02:40:12]

Given the subsystems you are filtering for, you shouldn't ever end up getting
DEVTYPE_UNKNOWN in the end, right?

[wjia(left Chromium), 2012/07/31 02:53:10]

That's correct. A DCHECK has been added.

+      base::SystemMonitor::DEVTYPE_UNKNOWN;
+  std::string subsystem(udev_device_get_subsystem(device));
+  for (size_t i = 0; i < arraysize(kSubsystemMap); ++i) {
+    if (subsystem == kSubsystemMap[i].subsystem) {
+      device_type = kSubsystemMap[i].device_type;
+      break;
+    }
+  }
+
+  base::SystemMonitor::Get()->ProcessDevicesChanged(device_type);
+}
+
+}  // namespace content