Change destruction order to fix potential invalid pointer dereference.

webrtc/modules/desktop_capture/screen_capturer_mac.mm

Index: webrtc/modules/desktop_capture/screen_capturer_mac.mm
diff --git a/webrtc/modules/desktop_capture/screen_capturer_mac.mm b/webrtc/modules/desktop_capture/screen_capturer_mac.mm
index 47885ee9d9d281fdb8b5019c8e59bf99343d14d4..3251e5a06509fc09aa37955f1302c444d3b22105 100644
--- a/webrtc/modules/desktop_capture/screen_capturer_mac.mm
+++ b/webrtc/modules/desktop_capture/screen_capturer_mac.mm
@@ -390,8 +390,8 @@ ScreenCapturerMac::ScreenCapturerMac(
 
 ScreenCapturerMac::~ScreenCapturerMac() {
   ReleaseBuffers();
-  display_stream_manager_->PrepareForSelfDestruction();
   UnregisterRefreshAndMoveHandlers();
+  display_stream_manager_->PrepareForSelfDestruction();
   dlclose(app_services_library_);
   dlclose(opengl_library_);
 }