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

Source/core/html/canvas/WebGLRenderingContext.cpp

Index: Source/core/html/canvas/WebGLRenderingContext.cpp
diff --git a/Source/core/html/canvas/WebGLRenderingContext.cpp b/Source/core/html/canvas/WebGLRenderingContext.cpp
index d6be7708079fd81171d48e41493f91efe90a97b9..eae14f99b97315fb24c888eb3f64aedf8540cdd4 100644
--- a/Source/core/html/canvas/WebGLRenderingContext.cpp
+++ b/Source/core/html/canvas/WebGLRenderingContext.cpp
@@ -84,9 +84,20 @@ PassOwnPtrWillBeRawPtr<WebGLRenderingContext> WebGLRenderingContext::create(HTML
         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;
     }