Add reference counter of DxgiDuplicatorController to unload DXGI components

webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc

Index: webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
diff --git a/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc b/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
index c17bd1481c7fffa9e09939e3fbcb75f70deaee87..e1a9febb77aba879484c112dc26db2d31d1ab8a6 100644
--- a/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
+++ b/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc
@@ -16,6 +16,7 @@
 #include <string>
 
 #include "webrtc/base/checks.h"
+#include "webrtc/base/logging.h"
 #include "webrtc/base/timeutils.h"
 #include "webrtc/modules/desktop_capture/desktop_capture_types.h"
 #include "webrtc/modules/desktop_capture/win/dxgi_frame.h"
@@ -25,6 +26,9 @@
 namespace webrtc {
 
 // static
+std::atomic_int DxgiDuplicatorController::refcount_(0);
+
+// static
 DxgiDuplicatorController* DxgiDuplicatorController::Instance() {
   // The static instance won't be deleted to ensure it can be used by other
   // threads even during program exiting.
@@ -32,13 +36,28 @@ DxgiDuplicatorController* DxgiDuplicatorController::Instance() {
   return instance;
 }
 
-DxgiDuplicatorController::DxgiDuplicatorController() = default;
+// static
+DxgiDuplicatorController::Reference DxgiDuplicatorController::GetReference() {
+  Reference result(Instance());
+  int refcount = (++refcount_);
+  RTC_DCHECK(refcount > 0);
+  return result;
+}
 
-DxgiDuplicatorController::~DxgiDuplicatorController() {
-  rtc::CritScope lock(&lock_);
-  Deinitialize();
+// static
+void DxgiDuplicatorController::ReferenceReleaser::operator()(
+    DxgiDuplicatorController* instance) const {
+  int refcount = (--refcount_);
+  RTC_DCHECK(refcount >= 0);
+  if (refcount == 0) {
+    LOG(LS_WARNING) << "Count of references reaches zero, "
+                       "DxgiDuplicatorController will be unloaded.";
+    instance->Unload();
+  }
 }
 
+DxgiDuplicatorController::DxgiDuplicatorController() = default;
+
 bool DxgiDuplicatorController::IsSupported() {
   rtc::CritScope lock(&lock_);
   return Initialize();
@@ -129,6 +148,11 @@ DxgiDuplicatorController::DoDuplicate(DxgiFrame* frame, int monitor_id) {
   return Result::DUPLICATION_FAILED;
 }
 
+void DxgiDuplicatorController::Unload() {
+  rtc::CritScope lock(&lock_);
+  Deinitialize();
+}
+
 void DxgiDuplicatorController::Unregister(const Context* const context) {
   rtc::CritScope lock(&lock_);
   if (ContextExpired(context)) {