Chrome Native Messaging Api not working on Linux
Ok, so I dug into the Chrome sources for my version (33.0.1750.117) and figured out that the json file is never read (and confirmed my finding using inotifywatch). I think (judging from this file line 143ff and this file) that the home directory is never actually looked into when the manifest file is searched.
However I came across a command line switch which can be used to locate the manifest files: --native-messaging-hosts="com.google.chrome.example.echo=~/.config/google-chrome/NativeMessagingHosts/com.google.chrome.example.echo.json". Even though this is no permanent solution it works for me, because I don't have root on the machine I'm developing on and can't write to /etc/opt/
I've found the same to be true on OSX with Chrome 33.0.1750.117.
You have to put it in /Library/Google/Chrome/NativeMessagingHosts/ and not in user's Library/Google/Chrome/NativeMessagingHosts/ folder.
(I'd comment but my reputation didn't allow it)
https://code.google.com/p/chromium/issues/detail?id=237873
According to this bug the user-level installation will be supported in Chrome-34