Bug 1808667 - Set pipewire flag in CreateDesktopCaptureOptions instead of in libwebrtc. r=ng

This restores the default value of the flag to verbatim libwebrtc code, and adds
a pref so it can be toggled off.

Differential Revision: https://phabricator.services.mozilla.com/D166036

dom/media/systemservices/video_engine/desktop_capture_impl.cc

@@ -344,6 +344,12 @@ static DesktopCaptureOptions CreateDesktopCaptureOptions() {
   }
 #endif
 
+#if defined(WEBRTC_USE_PIPEWIRE)
+  if (mozilla::StaticPrefs::media_webrtc_capture_allow_pipewire()) {
+    options.set_allow_pipewire(true);
+  }
+#endif
+
   return options;
 }
 

modules/libpref/init/StaticPrefList.yaml

@@ -10547,6 +10547,13 @@
   value: true
   mirror: always
 
+#if defined(MOZ_WIDGET_GTK)
+- name: media.webrtc.capture.allow-pipewire
+  type: RelaxedAtomicBool
+  value: true
+  mirror: always
+#endif
+
 - name: media.block-autoplay-until-in-foreground
   type: bool
 #if !defined(MOZ_WIDGET_ANDROID)

third_party/libwebrtc/modules/desktop_capture/desktop_capture_options.h

@@ -233,7 +233,7 @@ class RTC_EXPORT DesktopCaptureOptions {
   bool disable_effects_ = true;
   bool detect_updated_region_ = false;
 #if defined(WEBRTC_USE_PIPEWIRE)
-  bool allow_pipewire_ = true;
+  bool allow_pipewire_ = false;
   uint32_t width_ = 0;
   uint32_t height_ = 0;
 #endif