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

public/platform/WebGraphicsContext3D.h

 /*
  * Copyright (C) 2012 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 42 matching lines @@
 typedef int WGC3Dsizei;
 typedef unsigned WGC3Duint;
 typedef float WGC3Dfloat;
 typedef float WGC3Dclampf;
 typedef signed long int WGC3Dintptr;
 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
 // the OpenGL ES 2.0 API.
 class WebGraphicsContext3D : public WebNonCopyable {
 public:
     // Return value from getActiveUniform and getActiveAttrib.
     struct ActiveInfo {
         WebString name;
         WGC3Denum type;
@@ skipping 378 matching lines @@
     virtual void vertexAttribDivisorANGLE(WGC3Duint index, WGC3Duint divisor) { }
 
     // GL_EXT_multisampled_render_to_texture
     virtual void framebufferTexture2DMultisampleEXT(WGC3Denum target, WGC3Denum attachment, WGC3Denum textarget, WebGLId texture, WGC3Dint level, WGC3Dsizei samples) { }
     virtual void renderbufferStorageMultisampleEXT(WGC3Denum target, WGC3Dsizei samples, WGC3Denum internalformat, WGC3Dsizei width, WGC3Dsizei height) { };
 };
 
 } // namespace blink
 
 #endif