Packaging a GWT app to run completely offline NOT installed via a "marketplace" - gwt

Question

Theres a few questions similar to this, so I'll try to be clear as possible.
We have an existing, fairly large and complex, GWT webgame I have been asked to make work offline. It has to be offline in pretty much the strictest sense.
Imagine we have been told to make it work off a CD Rom.
So installation is allowed, but we cant expect the users to go to a Chrome/Firefox store and install it from there. It would need to be off the disc.
Likewise, altering of the browsers start-up flags would be unreasonable to expect of users.
Ideally, it would be nice if they just clicked a HTML file for the start page and it opened in their browsers of choice.
We successfully got it working this way in Firefox by adding;
"<add-linker name='xsiframe' />"
To our gwt.xml settings. This seems to solve any security issues FF has with local file access.
However, this does not solve the problem for Chrome.
The main game starts up, but various file requests are blocked due to security issues like these;
XMLHttpRequest cannot load file:///E:/Game%20projects/[Thorn]%20Game/ThornGame/text/messages_en.properties. Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, https, chrome-extension-resource.MyApplication-0.js:34053 com_google_gwt_http_client_RequestBuilder_$doSend__Lcom_google_gwt_http_client_RequestBuilder_2Ljava_lang_String_2Lcom_google_gwt_http_client_RequestCallback_2Lcom_google_gwt_http_client_Request_2 MyApplication-0.js:34053
Now I was aware same origin policy issues might popup as during development we often tested locally using flags in chrome to bi-pass them.
Thing is...now I dont know how to get around them when we cant use startup flags.
Obviously in the example given its just the .properties file GWT uses to get some language related text. I could dump that inline in one way or another.
However, its only one of many,many,many files being blocked.
The whole game was made to run off *.txt game scripts on the sever - to allow easy updating by non-coders. Really the actual GWT code is just an "engine" and all the XMLHttpRequested files supply the actual "game".
These files are of various types; csv, txt, ntlist, jam.
The last two being custom extensions for what are really just txt files.
All these files are blocked by chromes security. It seems from what I can make out only images are allowed to be accessed locally.
Having all these files compiled in would just be impossible, as they are not fixed in number (ie, one central .txt file determains various scene .txt files which in turn determain various object files and directory's...).
Putting all this into a bundle would be nightmare to create and maintain.
So in essence I need some way to supply a offline version of a GWT project that can access a large number of various files in its subdirectories without security issues.
So far all I can think of is;
A) Theres something I can tell chrome via html or gwt that allows these files to be read in Chrome like FF can. (I suspect this isn't possible).
An alternative to XMLHttpRequest maybe?
B) I need to somehow package a game+a webbrowser in a executable package that has permission to access files in its directory's. (http://www.appcelerator.com/titanium ? ?? ).
C) I need to package and have the user run a full webserver that can then deliver all these files in a XMLHttp accessible way.
D) Bit of a funny one...we cant tell the user to add flags to browser start up...but Maybe I could write a game installer which just detects if they have Chrome or Firefox. It then opens up the games html in their browser with the correct flags for them? This would open up security issues if they browse elsewhere with that instance though, so Id presumably need other flags to disable the url bar if that's possible.
I am happy to make various changes to our code to achieve any of this - but as mentioned above theres no way to determain all the files needing to be accessed at compile time.
And finally, of course, it all has to be as easy as possible for the end user.
Ideally just clicking a html file, or installing something no more complex then a standard windows program.
Thanks for reading this rather long explanation, any pointers and ideas would be very welcome. I especially will appreciate multiple different options or feedback from anyone that's done this.
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I accepted the suggestion to use Chromiumembedded below.
This works and does what I need (and much much more)
To help others that might want to use it, I specifically made two critical changes to the example project;
Because CEF needs a absolute path to the web apps local html, I wrote a c++ function to get the directory the .exe was launched from. This was a platform specific implementation, so if supporting a few OS's (which CEF does) be sure to write dedicated code for each.
Because my webapp will make use of local files, I enabled the Chrome flag for this by changing the browser settings;
browser_settings.file_access_from_file_urls = STATE_ENABLED;
These two changes were enough to get my app working, but it is obviously the bare minimum to make a application. Hopefully my finding will help others.

Answer 1

I'd suggest going the wrapper route. That is, provide a minimal browser implementation that opens your files directly. Options are Chromium Embedded[1]. If the nature of the application absolutely requires the files to be served as non-file urls then bundle a minimal webserver, have the on-disk executable start the server and open the bundled browser with whatever startup arguments you want.
[1] https://bitbucket.org/chromiumembedded/cef