From: Alex Chronopoulos <achronop@gmail.com>
Date: Tue, 17 Sep 2019 14:31:00 +0000
Subject: Bug 1581806 - Trigger devicechange event for audio and video input
 devices only. r=dminor

After Bug 1581193 devicechange notifications were triggered with any device change, not just video and audio devices. This patch limits down the notifications to only video and audio input devices change.

Differential Revision: https://phabricator.services.mozilla.com/D46147
Mercurial Revision: https://hg.mozilla.org/mozilla-central/rev/1feec83ee6f92a35de0d4b27ebea04e68a0d7ef0
---
 .../video_capture/windows/device_info_ds.cc   | 29 +++++++++++++++++--
 .../video_capture/windows/device_info_ds.h    |  1 +
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/modules/video_capture/windows/device_info_ds.cc b/modules/video_capture/windows/device_info_ds.cc
index 8543dce746..96db60c968 100644
--- a/modules/video_capture/windows/device_info_ds.cc
+++ b/modules/video_capture/windows/device_info_ds.cc
@@ -20,6 +20,18 @@
 namespace webrtc {
 namespace videocapturemodule {
 
+BOOL isCaptureDevice(DEV_BROADCAST_HDR *pHdr)
+{
+  if (pHdr == NULL) {
+    return FALSE;
+  }
+  if (pHdr->dbch_devicetype != DBT_DEVTYP_DEVICEINTERFACE) {
+    return FALSE;
+  }
+  DEV_BROADCAST_DEVICEINTERFACE* pDi = (DEV_BROADCAST_DEVICEINTERFACE*)pHdr;
+  return pDi->dbcc_classguid == KSCATEGORY_CAPTURE;
+}
+
 LRESULT CALLBACK WndProc(HWND hWnd, UINT uiMsg, WPARAM wParam, LPARAM lParam)
 {
     DeviceInfoDS* pParent;
@@ -35,7 +47,7 @@ LRESULT CALLBACK WndProc(HWND hWnd, UINT uiMsg, WPARAM wParam, LPARAM lParam)
     else if (uiMsg == WM_DEVICECHANGE)
     {
         pParent = (DeviceInfoDS*)GetWindowLongPtr(hWnd, GWLP_USERDATA);
-        if (pParent)
+        if (pParent && isCaptureDevice((PDEV_BROADCAST_HDR)lParam))
         {
             pParent->DeviceChange();
         }
@@ -56,7 +68,8 @@ DeviceInfoDS* DeviceInfoDS::Create() {
 DeviceInfoDS::DeviceInfoDS()
     : _dsDevEnum(NULL),
       _dsMonikerDevEnum(NULL),
-      _CoUninitializeIsRequired(true) {
+      _CoUninitializeIsRequired(true),
+      _hdevnotify(NULL) {
   // 1) Initialize the COM library (make Windows load the DLLs).
   //
   // CoInitializeEx must be called at least once, and is usually called only
@@ -111,6 +124,14 @@ DeviceInfoDS::DeviceInfoDS()
     _hwnd = CreateWindow(_wndClass.lpszClassName, NULL, 0, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL,
                          NULL, _hInstance, this);
+
+    DEV_BROADCAST_DEVICEINTERFACE di = { 0 };
+    di.dbcc_size = sizeof(di);
+    di.dbcc_devicetype  = DBT_DEVTYP_DEVICEINTERFACE;
+    di.dbcc_classguid  = KSCATEGORY_CAPTURE;
+
+    _hdevnotify = RegisterDeviceNotification(_hwnd, &di,
+                                             DEVICE_NOTIFY_WINDOW_HANDLE);
   }
 }
 
@@ -120,6 +141,10 @@ DeviceInfoDS::~DeviceInfoDS() {
   if (_CoUninitializeIsRequired) {
     CoUninitialize();
   }
+  if (_hdevnotify)
+  {
+    UnregisterDeviceNotification(_hdevnotify);
+  }
   if (_hwnd != NULL) {
     DestroyWindow(_hwnd);
   }
diff --git a/modules/video_capture/windows/device_info_ds.h b/modules/video_capture/windows/device_info_ds.h
index dc7b9b1a24..ed2a726d6f 100644
--- a/modules/video_capture/windows/device_info_ds.h
+++ b/modules/video_capture/windows/device_info_ds.h
@@ -96,6 +96,7 @@ class DeviceInfoDS : public DeviceInfoImpl {
   HWND _hwnd;
   WNDCLASS _wndClass;
   HINSTANCE _hInstance;
+  HDEVNOTIFY _hdevnotify;
 };
 }  // namespace videocapturemodule
 }  // namespace webrtc
-- 
2.34.1