Added GL_CHROMIUM_trace_marker feature as well as gpu_toplevel markers.

gpu/blink/webgraphicscontext3d_impl.h

Index: gpu/blink/webgraphicscontext3d_impl.h
diff --git a/gpu/blink/webgraphicscontext3d_impl.h b/gpu/blink/webgraphicscontext3d_impl.h
index 41a6d89411c29764b605cf7c8eb8a4bb24ed289b..11a3dc5c018fbd4bb3e549190d7456216cc3737d 100644
--- a/gpu/blink/webgraphicscontext3d_impl.h
+++ b/gpu/blink/webgraphicscontext3d_impl.h
@@ -493,6 +493,9 @@ class GPU_BLINK_EXPORT WebGraphicsContext3DImpl
   virtual void uniformValuebufferCHROMIUM(WGC3Dint location,
                                           WGC3Denum target,
                                           WGC3Denum subscription);
+  virtual void traceBeginCHROMIUM(const WGC3Dchar* category_name,
+                                  const WGC3Dchar* trace_name);
+  virtual void traceEndCHROMIUM();
 
   virtual void insertEventMarkerEXT(const WGC3Dchar* marker);
   virtual void pushGroupMarkerEXT(const WGC3Dchar* marker);