Add support for device removal/arrival detection with device type. For now this allows us to detect…

content/browser/system_message_window_win.cc

Index: content/browser/system_message_window_win.cc
diff --git a/content/browser/system_message_window_win.cc b/content/browser/system_message_window_win.cc
index ca31feb21f7a1358d25b51e42f5f052a9e844db6..2394327d7f0ca181aa5eda60bd985968c3f76bbc 100644
--- a/content/browser/system_message_window_win.cc
+++ b/content/browser/system_message_window_win.cc
@@ -4,20 +4,75 @@
 
 #include "content/browser/system_message_window_win.h"
 
-#include <windows.h>
 #include <dbt.h>
+#include <ks.h>
+#include <ksmedia.h>
 
 #include "base/logging.h"
 #include "base/system_monitor/system_monitor.h"
 #include "base/win/wrapped_window_proc.h"
 
-static const wchar_t* const WindowClassName = L"Chrome_SystemMessageWindow";
+namespace {
+const wchar_t kWindowClassName[] = L"Chrome_SystemMessageWindow";
+
+// A static map from a device category guid to base::SystemMonitor::DeviceType.
+struct {
+  const GUID device_category;
+  const base::SystemMonitor::DeviceType device_type;
+} const kDeviceCategoryMap[] = {
+  { KSCATEGORY_AUDIO, base::SystemMonitor::DEVTYPE_AUDIO_CAPTURE },
+  { KSCATEGORY_VIDEO, base::SystemMonitor::DEVTYPE_VIDEO_CAPTURE },
+};
+}  // namespace
+
+// Manages the device notification handles for SystemMessageWindowWin.
+class SystemMessageWindowWin::DeviceNotifications {
+ public:
+  explicit DeviceNotifications(HWND hwnd) : notifications_() {
+    Register(hwnd);
+  }
+
+  ~DeviceNotifications() {
+    Unregister();
+  }
+
+  void Register(HWND hwnd) {
+    // Request to receive device notifications.  All applications receive basic
+    // notifications via WM_DEVICECHANGE but in order to receive detailed device
+    // arrival and removal messages, we need to register.
+    DEV_BROADCAST_DEVICEINTERFACE filter = {0};
+    filter.dbcc_size = sizeof(filter);
+    filter.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
+    for (int i = 0; i < arraysize(kDeviceCategoryMap); ++i) {
+      filter.dbcc_classguid = kDeviceCategoryMap[i].device_category;
+      DCHECK_EQ(notifications_[i], static_cast<HDEVNOTIFY>(NULL));
+      notifications_[i] = RegisterDeviceNotification(
+          hwnd, &filter, DEVICE_NOTIFY_WINDOW_HANDLE);
+      DPLOG_IF(ERROR, !notifications_[i])
+          << "RegisterDeviceNotification failed";
+    }
+  }
+
+  void Unregister() {
+    for (int i = 0; i < arraysize(notifications_); ++i) {
+      if (notifications_[i]) {
+        UnregisterDeviceNotification(notifications_[i]);
+        notifications_[i] = NULL;
+      }
+    }
+  }
+
+ private:
+  HDEVNOTIFY notifications_[arraysize(kDeviceCategoryMap)];
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(DeviceNotifications);
+};
 
 
 SystemMessageWindowWin::SystemMessageWindowWin() {
   WNDCLASSEX window_class;
   base::win::InitializeWindowClass(
-      WindowClassName,
+      kWindowClassName,
       &base::win::WrappedWindowProc<SystemMessageWindowWin::WndProcThunk>,
       0, 0, 0, NULL, NULL, NULL, NULL, NULL,
       &window_class);
@@ -25,25 +80,61 @@ SystemMessageWindowWin::SystemMessageWindowWin() {
   ATOM clazz = RegisterClassEx(&window_class);
   DCHECK(clazz);
 
-  window_ = CreateWindow(WindowClassName,
+  window_ = CreateWindow(kWindowClassName,
                          0, 0, 0, 0, 0, 0, 0, 0, instance_, 0);
   SetWindowLongPtr(window_, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(this));
+  device_notifications_.reset(new DeviceNotifications(window_));
 }
 
 SystemMessageWindowWin::~SystemMessageWindowWin() {
   if (window_) {
     DestroyWindow(window_);
-    UnregisterClass(WindowClassName, instance_);
+    UnregisterClass(kWindowClassName, instance_);
   }
 }
 
-LRESULT SystemMessageWindowWin::OnDeviceChange(UINT event_type, DWORD data) {
+LRESULT SystemMessageWindowWin::OnDeviceChange(UINT event_type, LPARAM data) {
   base::SystemMonitor* monitor = base::SystemMonitor::Get();
+  base::SystemMonitor::DeviceType device_type =
+      base::SystemMonitor::DEVTYPE_UNKNOWN;
   switch (event_type) {
     case DBT_DEVNODES_CHANGED:
-      monitor->ProcessDevicesChanged(base::SystemMonitor::DEVTYPE_UNKNOWN);
+      // For this notification, we're happy with the default DEVTYPE_UNKNOWN.
+      break;
+
+    case DBT_DEVICEREMOVECOMPLETE:
+    case DBT_DEVICEARRIVAL: {
+      // This notification has more details about the specific device that
+      // was added or removed.  See if this is a category we're interested
+      // in monitoring and if so report the specific device type.  If we don't
+      // find the category in our map, ignore the notification and do not
+      // notify the system monitor.
+      DEV_BROADCAST_DEVICEINTERFACE* device_interface =
+          reinterpret_cast<DEV_BROADCAST_DEVICEINTERFACE*>(data);
+      DCHECK_EQ(device_interface->dbcc_devicetype,
+                static_cast<DWORD>(DBT_DEVTYP_DEVICEINTERFACE));
+      for (int i = 0; i < arraysize(kDeviceCategoryMap); ++i) {
+        if (kDeviceCategoryMap[i].device_category ==
+            device_interface->dbcc_classguid) {
+          device_type = kDeviceCategoryMap[i].device_type;
+          break;
+        }
+      }
+
+      // Devices that we do not have a DEVTYPE_ for, get detected via
+      // DBT_DEVNODES_CHANGED, so we avoid sending additional notifications
+      // for those here.
+      if (device_type == base::SystemMonitor::DEVTYPE_UNKNOWN)
+        return TRUE;
       break;
+    }
+
+    default:
+      return TRUE;
   }
+
+  monitor->ProcessDevicesChanged(device_type);
+
   return TRUE;
 }
 
@@ -51,8 +142,7 @@ LRESULT CALLBACK SystemMessageWindowWin::WndProc(HWND hwnd, UINT message,
                                                  WPARAM wparam, LPARAM lparam) {
   switch (message) {
     case WM_DEVICECHANGE:
-      return OnDeviceChange(static_cast<UINT>(wparam),
-                            static_cast<DWORD>(lparam));
+      return OnDeviceChange(static_cast<UINT>(wparam), lparam);
     default:
       break;
   }