CEF3: Add Native Client support

[GoogleCodeExporter]

Using cef_binary_3.1180.719_windows, if I direct my web browser to my own 
Native Client application on an HTTP server I stared, I get "Couldn't load 
plug-in" in the <embed> tag.

What steps will reproduce the problem?
1. Install Native Client SDK: https://developers.google.com/native-client/sdk/
2. Start web server with demo applications
3. Browse to local server with cefclient, and it cannot load the plugin.

Also, if you look at the 'Plugin Info' page in cefclient, many plugins are 
listed but not Native Client; compare this with regular chrome 'about://flags', 
which does say there is a Native Client plugin installed.

What is the expected output? What do you see instead?

Expected: Native client plugin loading successfully.

Seen: error loading plugin.

What version of the product are you using? On what operating system?

cef_binary_3.1180.719_windows

Please provide any additional information below.

Original issue reported on code.google.com by mad....@gmail.com on 2 Sep 2012 at 4:03