Enable creation of offscreen contexts which own their backing surface.

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 28 matching lines @@
 #include "core/frame/Settings.h"
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLImageElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/ImageData.h"
 #include "core/inspector/ConsoleMessage.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/layout/LayoutBox.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
+#include "core/origin_trials/OriginTrials.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "modules/webgl/ANGLEInstancedArrays.h"
 #include "modules/webgl/EXTBlendMinMax.h"
 #include "modules/webgl/EXTFragDepth.h"
 #include "modules/webgl/EXTShaderTextureLOD.h"
 #include "modules/webgl/EXTTextureFilterAnisotropic.h"
 #include "modules/webgl/GLStringQuery.h"
 #include "modules/webgl/OESElementIndexUint.h"
 #include "modules/webgl/OESStandardDerivatives.h"
 #include "modules/webgl/OESTextureFloat.h"
@@ skipping 555 matching lines @@
     ScriptState* scriptState,
     const CanvasContextCreationAttributes& attributes,
     unsigned webGLVersion) {
   // Exactly one of these must be provided.
   DCHECK_EQ(!canvas, !!scriptState);
   // The canvas is only given on the main thread.
   DCHECK(!canvas || isMainThread());
 
   Platform::ContextAttributes contextAttributes =
       toPlatformContextAttributes(attributes, webGLVersion);
+
+  // If there's a possibility this context may be used with WebVR make sure it
+  // is created with an offscreen surface that can be swapped out for a
+  // VR-specific surface if needed. We can only check the origin trial
+  // if called with a scriptState, not for a canvas.
+  if (RuntimeEnabledFeatures::webVREnabled() ||
+      (scriptState &&
+       OriginTrials::webVREnabled(scriptState->getExecutionContext()))) {
+    contextAttributes.supportOwnOffscreenSurface = true;
+  }
+
   Platform::GraphicsInfo glInfo;
   std::unique_ptr<WebGraphicsContext3DProvider> contextProvider;
   const auto& url = canvas ? canvas->document().topDocument().url()
                            : scriptState->getExecutionContext()->url();
   if (isMainThread()) {
     contextProvider = WTF::wrapUnique(
         Platform::current()->createOffscreenGraphicsContext3DProvider(
             contextAttributes, url, 0, &glInfo));
   } else {
     contextProvider =
@@ skipping 7140 matching lines @@
 
 void WebGLRenderingContextBase::getHTMLOrOffscreenCanvas(
     HTMLCanvasElementOrOffscreenCanvas& result) const {
   if (canvas())
     result.setHTMLCanvasElement(canvas());
   else
     result.setOffscreenCanvas(getOffscreenCanvas());
 }
 
 }  // namespace blink