Expose WEBGL_debug_renderer_info through a chromium finch experiment.

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 9e0f68e5f5d6ad35f8a3bb998145882eebcd52e2..0bfaca7674615d16ba34762c225a0bbb2d3a9e32 100644
--- a/Source/core/html/canvas/WebGLRenderingContext.cpp
+++ b/Source/core/html/canvas/WebGLRenderingContext.cpp
@@ -624,7 +624,7 @@ WebGLRenderingContext::WebGLRenderingContext(HTMLCanvasElement* passedCanvas, Pa
     registerExtension<WebGLDrawBuffers>(m_webglDrawBuffers, DraftExtension);
 
     // Register privileged extensions.
-    registerExtension<WebGLDebugRendererInfo>(m_webglDebugRendererInfo, PrivilegedExtension);
+    registerExtension<WebGLDebugRendererInfo>(m_webglDebugRendererInfo, WebGLDebugRendererInfoExtension);
     registerExtension<WebGLDebugShaders>(m_webglDebugShaders, PrivilegedExtension);
 }
 
@@ -728,6 +728,14 @@ bool WebGLRenderingContext::allowPrivilegedExtensions() const
     return false;
 }
 
+bool WebGLRenderingContext::allowWebGLDebugRendererInfo() const
+{
+    if (allowPrivilegedExtensions())
+        return true;
+    Frame* frame = canvas()->document().frame();
+    return frame && frame->loader().client()->allowWebGLDebugRendererInfo();
+}
+
 void WebGLRenderingContext::addCompressedTextureFormat(GC3Denum format)
 {
     if (!m_compressedTextureFormats.contains(format))
@@ -2177,6 +2185,8 @@ PassRefPtr<WebGLExtension> WebGLRenderingContext::getExtension(const String& nam
     for (size_t i = 0; i < m_extensions.size(); ++i) {
         ExtensionTracker* tracker = m_extensions[i];
         if (tracker->matchesNameWithPrefixes(name)) {
+            if (tracker->webglDebugRendererInfo() && !allowWebGLDebugRendererInfo())
+                return 0;
             if (tracker->privileged() && !allowPrivilegedExtensions())
                 return 0;
             if (tracker->draft() && !RuntimeEnabledFeatures::webGLDraftExtensionsEnabled())
@@ -2630,6 +2640,8 @@ Vector<String> WebGLRenderingContext::getSupportedExtensions()
 
     for (size_t i = 0; i < m_extensions.size(); ++i) {
         ExtensionTracker* tracker = m_extensions[i];
+        if (tracker->webglDebugRendererInfo() && !allowWebGLDebugRendererInfo())
+            continue;
         if (tracker->privileged() && !allowPrivilegedExtensions())
             continue;
         if (tracker->draft() && !RuntimeEnabledFeatures::webGLDraftExtensionsEnabled())