Support offscreen contexts which own their backing surface

content/public/common/content_features.cc

Index: content/public/common/content_features.cc
diff --git a/content/public/common/content_features.cc b/content/public/common/content_features.cc
index e9a64b515cdcca10ad73e2aaf61da1c77ad5ffef..f47b82ade0654523fb8587c66a6b16ec93c8e1a6 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -253,6 +253,10 @@ const base::Feature kWebRtcHWH264Encoding{
 // https://wicg.github.io/webusb
 const base::Feature kWebUsb{"WebUSB", base::FEATURE_ENABLED_BY_DEFAULT};
 
+// Enables WebVR experimental rendering optimizations.
+const base::Feature kWebVRExperimentalRendering{
+    "WebVRExperimentalRendering", base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Make sendBeacon throw for a Blob with a non simple type.
 const base::Feature kSendBeaconThrowForBlobWithNonSimpleType{
     "SendBeaconThrowForBlobWithNonSimpleType",