Beginning of JS Mojo API to GL

gin/arguments.h

Index: gin/arguments.h
diff --git a/gin/arguments.h b/gin/arguments.h
index 104152ab908fd8beecb0c3b50e6eea9802a03a48..ec4ae80e88219d5fcb15ecb770bfdf429c672849 100644
--- a/gin/arguments.h
+++ b/gin/arguments.h
@@ -61,10 +61,10 @@ class GIN_EXPORT Arguments {
     info_->GetReturnValue().Set(ConvertToV8(isolate_, val));
   }
 
-  v8::Handle<v8::Value> PeekNext();
+  v8::Handle<v8::Value> PeekNext() const;
 
-  void ThrowError();
-  void ThrowTypeError(const std::string& message);
+  void ThrowError() const;
+  void ThrowTypeError(const std::string& message) const;
 
   v8::Isolate* isolate() const { return isolate_; }