Implement offscreenCanvas.getContext('webgl') on a worker thread

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

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
index 8d225171f7490da6c60aa362ee397a2ccaf55959..f51ff9a1fff1df4e75b32cb836903ec48c755886 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
@@ -36,6 +36,7 @@
 #include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "modules/webgl/WebGLContextAttributes.h"
+#include "modules/webgl/WebGLContextProviderCreationInfo.h"
 #include "modules/webgl/WebGLExtensionName.h"
 #include "modules/webgl/WebGLTexture.h"
 #include "modules/webgl/WebGLVertexArrayObjectBase.h"
@@ -44,6 +45,8 @@
 #include "platform/graphics/gpu/DrawingBuffer.h"
 #include "platform/graphics/gpu/Extensions3DUtil.h"
 #include "platform/graphics/gpu/WebGLImageConversion.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebGraphicsContext3DProvider.h"
 #include "third_party/khronos/GLES2/gl2.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/text/WTFString.h"
@@ -83,6 +86,7 @@ class OESTextureFloatLinear;
 class OESTextureHalfFloat;
 class OESTextureHalfFloatLinear;
 class OESVertexArrayObject;
+class WaitableEvent;
 class WebGLActiveInfo;
 class WebGLBuffer;
 class WebGLCompressedTextureASTC;
@@ -1090,6 +1094,9 @@ protected:
 
 private:
     WebGLRenderingContextBase(HTMLCanvasElement*, OffscreenCanvas*, PassOwnPtr<WebGraphicsContext3DProvider>, const WebGLContextAttributes&);
+    static PassOwnPtr<WebGraphicsContext3DProvider> createContextProviderInternal(HTMLCanvasElement*, ScriptState*, WebGLContextAttributes, unsigned);
+    static void createContextProviderOnMainThread(WebGLContextProviderCreationInfo*, WaitableEvent*);
+    static PassOwnPtr<WebGraphicsContext3DProvider> createContextProviderOnWorkerThread(Platform::ContextAttributes, Platform::GraphicsInfo, ScriptState*);
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());