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

public/platform/Platform.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 539 matching lines @@
     virtual void histogramEnumeration(const char* name, int sample, int boundaryValue) { }
     // Unlike enumeration histograms, sparse histograms only allocate memory for non-empty buckets.
     virtual void histogramSparse(const char* name, int sample) { }
 
 
     // GPU ----------------------------------------------------------------
     //
     // May return null if GPU is not supported.
     // Returns newly allocated and initialized offscreen WebGraphicsContext3D instance.
     // Passing an existing context to shareContext will create the new context in the same share group as the passed context.
-    virtual WebGraphicsContext3D* createOffscreenGraphicsContext3D(const WebGraphicsContext3D::Attributes&, WebGraphicsContext3D* shareContext) { return 0; }
+    virtual WebGraphicsContext3D* createOffscreenGraphicsContext3D(const WebGraphicsContext3D::Attributes&, WebGraphicsContext3D* shareContext, WebGLInfo& glInfo) { return 0; }

[piman, 2014/10/10 20:23:06]

Please pass output params by pointer, not (non-const) references.

[Ken Russell (switch to Gerrit), 2014/10/10 20:47:38]

Also, figure out a way to avoid temporarily breaking the override in Chromium,
whether this means temporarily overriding both the old and new signature in
Chromium, or temporarily having both signatures as virtual in Blink and having
the new one temporarily delegate to the old one.

[sivag, 2014/10/27 13:33:51]

Done.

     virtual WebGraphicsContext3D* createOffscreenGraphicsContext3D(const WebGraphicsContext3D::Attributes&) { return 0; }
 
     // Returns a newly allocated and initialized offscreen context provider. The provider may return a null
     // graphics context if GPU is not supported.
     virtual WebGraphicsContext3DProvider* createSharedOffscreenGraphicsContext3DProvider() { return 0; }
 
     // Returns true if the platform is capable of producing an offscreen context suitable for accelerating 2d canvas.
     // This will return false if the platform cannot promise that contexts will be preserved across operations like
     // locking the screen or if the platform cannot provide a context with suitable performance characteristics.
     //
@@ skipping 68 matching lines @@
 
     virtual WebGeofencingProvider* geofencingProvider() { return 0; }
 
 protected:
     virtual ~Platform() { }
 };
 
 } // namespace blink
 
 #endif