Bug 1726063 - Remove option to use BasicLayerManager. r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D122796

modules/libpref/init/StaticPrefList.yaml

@@ -4836,11 +4836,6 @@
   value: true
   mirror: always
 
-- name: gfx.basic_layer_manager.force_enabled
-  type: RelaxedAtomicBool
-  value: false
-  mirror: always
-
 #  Whether to enable LayerScope tool and default listening port.
 - name: gfx.layerscope.enabled
   type: RelaxedAtomicBool

widget/PuppetWidget.cpp

@@ -602,13 +602,7 @@ WindowRenderer* PuppetWidget::GetWindowRenderer() {
     if (XRE_IsParentProcess()) {
       // On the parent process there is no CompositorBridgeChild which confuses
       // some layers code, so we use basic layers instead. Note that we create
-      // a non-retaining layer manager since we don't care about performance.
-      if (StaticPrefs::gfx_basic_layer_manager_force_enabled()) {
-        mWindowRenderer =
-            new BasicLayerManager(BasicLayerManager::BLM_OFFSCREEN);
-      } else {
-        mWindowRenderer = new FallbackRenderer;
-      }
+      mWindowRenderer = new FallbackRenderer;
       return mWindowRenderer;
     }
 

widget/nsBaseWidget.cpp

@@ -1533,11 +1533,7 @@ WindowRenderer* nsBaseWidget::GetWindowRenderer() {
 }
 
 WindowRenderer* nsBaseWidget::CreateBasicLayerManager() {
-  if (StaticPrefs::gfx_basic_layer_manager_force_enabled()) {
-    return new BasicLayerManager(this);
-  } else {
-    return new FallbackRenderer;
-  }
+  return new FallbackRenderer;
 }
 
 CompositorBridgeChild* nsBaseWidget::GetRemoteRenderer() {