Bug 1645579 - Disable RecycleAllocator for RDD process when WebRender is disabled on Mac r=nical

Recycling caused rendering problem on a MacOS PC with OpenGL compositor. TextureHost reuse with OpenGL compositor seemed to have a problem.

Adds pref layers.recycle-allocator-rdd for disable/enable the RecycleAllocator.

Differential Revision: https://phabricator.services.mozilla.com/D79639

gfx/layers/ImageContainer.cpp

@@ -22,6 +22,7 @@
 #include "mozilla/layers/SharedSurfacesChild.h"  // for SharedSurfacesAnimation
 #include "mozilla/layers/SharedRGBImage.h"
 #include "mozilla/layers/TextureClientRecycleAllocator.h"
+#include "mozilla/StaticPrefs_layers.h"
 #include "mozilla/gfx/gfxVars.h"
 #include "nsISupportsUtils.h"  // for NS_IF_ADDREF
 #include "YCbCrUtils.h"        // for YCbCr conversions
@@ -422,6 +423,19 @@ void ImageContainer::EnsureRecycleAllocatorForRDD(
     return;
   }
 
+  bool useRecycleAllocator =
+      StaticPrefs::layers_recycle_allocator_rdd_AtStartup();
+#ifdef XP_MACOSX
+  // Disable RecycleAllocator for RDD on MacOS without WebRender.
+  // Recycling caused rendering artifact on a MacOS PC with OpenGL compositor.
+  if (!gfxVars::UseWebRender()) {
+    useRecycleAllocator = false;
+  }
+#endif
+  if (!useRecycleAllocator) {
+    return;
+  }
+
   static const uint32_t MAX_POOLED_VIDEO_COUNT = 5;
 
   mRecycleAllocator =

modules/libpref/init/StaticPrefList.yaml

@@ -5430,6 +5430,11 @@
   value: true
   mirror: once
 
+- name: layers.recycle-allocator-rdd
+  type: bool
+  value: true
+  mirror: once
+
 #---------------------------------------------------------------------------
 # Prefs starting with "layout."
 #---------------------------------------------------------------------------