Added GL_CHROMIUM_trace_marker functions to WebGraphicsContext3D.

public/platform/WebGraphicsContext3D.h

Index: public/platform/WebGraphicsContext3D.h
diff --git a/public/platform/WebGraphicsContext3D.h b/public/platform/WebGraphicsContext3D.h
index 3b285c9384c85df3ab7d19b1d11d7992175feb28..a0418f8721590d3f1ec474859220b17645e69814 100644
--- a/public/platform/WebGraphicsContext3D.h
+++ b/public/platform/WebGraphicsContext3D.h
@@ -432,6 +432,10 @@ public:
     virtual void pushGroupMarkerEXT(const WGC3Dchar* marker) { }
     virtual void popGroupMarkerEXT(void) { }
 
+    // GL_CHROMIUM_trace_marker
+    virtual void traceBeginCHROMIUM(const WGC3Dchar* category, const WGC3Dchar* trace) { }
+    virtual void traceEndCHROMIUM() { }
+
     // GL_OES_vertex_array_object
     virtual WebGLId createVertexArrayOES() { return 0; }
     virtual void deleteVertexArrayOES(WebGLId array) { }