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 0ec433698eb200967e720a8baf3e32f7bff34357..1f1ce7e2f95b3d598f6a1cf4680b1266880e4aeb 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
@@ -45,6 +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 "wtf/OwnPtr.h"
 #include "wtf/text/WTFString.h"
 
@@ -83,6 +85,7 @@ class OESTextureFloatLinear;
 class OESTextureHalfFloat;
 class OESTextureHalfFloatLinear;
 class OESVertexArrayObject;
+class WaitableEvent;
 class WebGLActiveInfo;
 class WebGLBuffer;
 class WebGLCompressedTextureASTC;
@@ -1077,6 +1080,27 @@ protected:
 
 private:
     WebGLRenderingContextBase(HTMLCanvasElement*, OffscreenCanvas*, PassOwnPtr<WebGraphicsContext3DProvider>, const WebGLContextAttributes&);
+    static PassOwnPtr<WebGraphicsContext3DProvider> createWebGraphicsContext3DProviderInternal(HTMLCanvasElement*, ScriptState*, WebGLContextAttributes, unsigned);
+    class createWebGraphicsContext3DProviderUtils {
+    public:
+        createWebGraphicsContext3DProviderUtils(Platform::ContextAttributes contextAttributes, Platform::GraphicsInfo glInfo, ScriptState* scriptState)
+        {
+            m_contextAttributes = contextAttributes;
+            m_glInfo = glInfo;
+            m_scriptState = scriptState;
+        }
+        Platform::ContextAttributes contextAttributes() { return m_contextAttributes; }
+        Platform::GraphicsInfo glInfo() { return m_glInfo; }
+        ScriptState* scriptState() { return m_scriptState; }
+        void setContextProvider(PassOwnPtr<WebGraphicsContext3DProvider> provider) { m_provider = std::move(provider); }
+        PassOwnPtr<WebGraphicsContext3DProvider> releaseContextProvider() { return m_provider.release(); }
+    private:
+        Platform::ContextAttributes m_contextAttributes;
+        Platform::GraphicsInfo m_glInfo;
+        ScriptState* m_scriptState;
+        OwnPtr<WebGraphicsContext3DProvider> m_provider;
+    };
+    static void createWebGraphicsContext3DProviderMainThread(createWebGraphicsContext3DProviderUtils*, WaitableEvent*);
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());