[WebGL-blink] Return meaningful information in WebGL context creation error message

public/platform/WebGraphicsContext3D.h

Index: public/platform/WebGraphicsContext3D.h
diff --git a/public/platform/WebGraphicsContext3D.h b/public/platform/WebGraphicsContext3D.h
index 2a8f47445006e3a7071b4e5cbfce63eeebd8a24e..c9136ff1dffffb3131a8d21c35d725c10a5c46df 100644
--- a/public/platform/WebGraphicsContext3D.h
+++ b/public/platform/WebGraphicsContext3D.h
@@ -60,6 +60,12 @@ typedef signed long int WGC3Dsizeiptr;
 // Typedef for server-side objects like OpenGL textures and program objects.
 typedef WGC3Duint WebGLId;
 
+struct WebGLInfo {
+    WebString vendorInfo;
+    WebString rendererInfo;
+    WebString driverVersion;
+};
+
 // This interface abstracts the operations performed by the
 // GraphicsContext3D in order to implement WebGL. Nearly all of the
 // methods exposed on this interface map directly to entry points in