Bug 1531417 - enable shared buffer provider for software canvas on all platforms. r=nical

dom/canvas/CanvasRenderingContext2D.cpp

@@ -1354,6 +1354,13 @@ bool CanvasRenderingContext2D::TrySharedTarget(
     return false;
   }
 
+#ifdef XP_WIN
+  // Bug 1285271 - Disable shared buffer provider on Windows with D2D due to instability
+  if (gfxPlatform::GetPlatform()->GetPreferredCanvasBackend() == BackendType::DIRECT2D1_1) {
+    return false;
+  }
+#endif
+
   RefPtr<LayerManager> layerManager =
       LayerManagerFromCanvasElement(mCanvasElement);
 

modules/libpref/init/all.js

@@ -5082,15 +5082,6 @@ pref("layers.prefer-opengl", false);
 // Copy-on-write canvas
 pref("layers.shared-buffer-provider.enabled", true);
 
-#ifdef XP_WIN
-pref("layers.shared-buffer-provider.enabled", false);
-#endif
-
-#ifdef XP_MACOSX
-// cf. Bug 1324908
-pref("layers.shared-buffer-provider.enabled", false);
-#endif
-
 // Force all possible layers to be always active layers
 pref("layers.force-active", false);