[WebGL] Return meaningful information in WebGL context creation error message.

Source/core/html/canvas/WebGLRenderingContext.cpp

 /*
  * Copyright (C) 2009 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 66 matching lines @@
         return nullptr;
     }
 
     // The only situation that attrs is null is through Document::getCSSCanvasContext().
     RefPtrWillBeRawPtr<WebGLContextAttributes> defaultAttrs = nullptr;
     if (!attrs) {
         defaultAttrs = WebGLContextAttributes::create();
         attrs = defaultAttrs.get();
     }
     blink::WebGraphicsContext3D::Attributes attributes = attrs->attributes(document.topDocument().url().string(), settings, 1);
-    OwnPtr<blink::WebGraphicsContext3D> context = adoptPtr(blink::Platform::current()->createOffscreenGraphicsContext3D(attributes, 0));
+    blink::WebGLInfo glInfo;
+    OwnPtr<blink::WebGraphicsContext3D> context = adoptPtr(blink::Platform::current()->createOffscreenGraphicsContext3D(attributes, 0, &glInfo));
     if (!context) {
-        canvas->dispatchEvent(WebGLContextEvent::create(EventTypeNames::webglcontextcreationerror, false, true, "Could not create a WebGL context."));
+        String statusMessage("Could not create a WebGL context for");
+        statusMessage.append("VendorInfo= ");

[Ken Russell (switch to Gerrit), 2014/11/04 00:37:49]

Combine these two constant strings. Add space between "for" and "VendorInfo".

[sivag, 2014/11/04 12:33:32]

Done.

+        statusMessage.append(glInfo.vendorInfo);
+        statusMessage.append(",");
+        statusMessage.append("RendererInfo= ");

[Ken Russell (switch to Gerrit), 2014/11/04 00:37:49]

Combine the adjacent constant strings here and below.

[sivag, 2014/11/04 12:33:32]

Done.

+        statusMessage.append(glInfo.rendererInfo);
+        statusMessage.append(",");
+        statusMessage.append("DriverInfo= ");
+        statusMessage.append(glInfo.driverVersion);
+        statusMessage.append(",");
+        canvas->dispatchEvent(WebGLContextEvent::create(EventTypeNames::webglcontextcreationerror, false, true, statusMessage));
         return nullptr;
     }
 
     OwnPtr<Extensions3DUtil> extensionsUtil = Extensions3DUtil::create(context.get());
     if (!extensionsUtil)
         return nullptr;
     if (extensionsUtil->supportsExtension("GL_EXT_debug_marker"))
         context->pushGroupMarkerEXT("WebGLRenderingContext");
 
     OwnPtrWillBeRawPtr<WebGLRenderingContext> renderingContext = adoptPtrWillBeNoop(new WebGLRenderingContext(canvas, context.release(), attrs));
@@ skipping 65 matching lines @@
     visitor->trace(m_webglDrawBuffers);
     visitor->trace(m_webglCompressedTextureATC);
     visitor->trace(m_webglCompressedTextureETC1);
     visitor->trace(m_webglCompressedTexturePVRTC);
     visitor->trace(m_webglCompressedTextureS3TC);
     visitor->trace(m_webglDepthTexture);
     WebGLRenderingContextBase::trace(visitor);
 }
 
 } // namespace blink