Correct the OffscreenCanvas.getContext API

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContext.h

Index: third_party/WebKit/Source/modules/webgl/WebGL2RenderingContext.h
diff --git a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContext.h b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContext.h
index 7ade440b570a1d70b2f50317bd5600e6d58d5766..329e2bcb0f97b8727ea83adeb1dd3d2bbc357115 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContext.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContext.h
@@ -32,6 +32,10 @@ class WebGL2RenderingContext : public WebGL2RenderingContextBase {
     CanvasRenderingContext* create(HTMLCanvasElement*,
                                    const CanvasContextCreationAttributes&,
                                    Document&) override;
+    CanvasRenderingContext* create(
+        ScriptState*,
+        OffscreenCanvas*,
+        const CanvasContextCreationAttributes&) override;
     CanvasRenderingContext::ContextType getContextType() const override {
       return CanvasRenderingContext::ContextWebgl2;
     }
@@ -59,6 +63,11 @@ class WebGL2RenderingContext : public WebGL2RenderingContextBase {
       std::unique_ptr<WebGraphicsContext3DProvider>,
       const CanvasContextCreationAttributes& requestedAttributes);
 
+  WebGL2RenderingContext(
+      OffscreenCanvas* passedOffscreenCanvas,
+      std::unique_ptr<WebGraphicsContext3DProvider>,
+      const CanvasContextCreationAttributes& requestedAttributes);
+
   Member<EXTColorBufferFloat> m_extColorBufferFloat;
   Member<EXTDisjointTimerQueryWebGL2> m_extDisjointTimerQueryWebGL2;
   Member<EXTTextureFilterAnisotropic> m_extTextureFilterAnisotropic;