Overriding Chromium's internal protocol handlers (mailto:, news:, etc)

Question

After reading many posts on different forums, I have found that overriding Chromium's internal protocol handlers is notoriously difficult. Some, like mailto:, use a hardcoded command name like xdg-email which doesn't work very well when not using one of the major desktops, while others don't work as expected for any number of reasons.
Which is why I've come up with a way to add any user-defined protocol that Chromium doesn't already handle using xdg-open.
The following example deals with adding an override for the mailto: protocol handler, to have it use xdg-open instead of xdg-email to start the email client.
The process is in 3 steps:
1. Add a .desktop file for the protocol handler override
2. Tell the system to use the protocol handler override
3. Tell Chromium to use the protocol handler override
Step 1: Create the file $HOME/.local/share/applications/chromium-mailto.desktop with the following contents:
[Desktop Entry]
Version=1.0
Name=Chromium mailto: override
Comment=Override the Chromium mailto: protocol handler
GenericName=Override the Chromium mailto: protocol handler
Exec=xdg-open $(echo %u|perl -pe 's/^x-chromium-mailto://; tr/+/ /; s/%([a-fA-F0-9]{2,2})/chr(hex($1))/eg;')
Terminal=false
Type=Application
MimeType=x-scheme-handler/x-chromium-mailto
NoDisplay=true
Step 2: Tell the system about the new MIME type
In a terminal, execute the following command:
$ xdg-mime default chromium-mailto.desktop x-scheme-handler/x-chromium-mailto
Note: the path to the .desktop file must be relative to $HOME/.local/share/applications !
Step 3: Tell Chromium to use the protocol handler override
First, close all open Chromium windows. This is very important for the following changes to 'take'!
Assuming you use the Default profile in Chromium, open the following file in an editor: $HOME/.config/chromium/Default/Preferences
Within the curly braces, for example under the lines:
"cloud_print": {
"email": ""
add the following:
"custom_handlers": {
"enabled": true,
"registered_protocol_handlers": [ {
"default": true,
"protocol": "mailto",
"title": "mailto: override",
"url": "x-chromium-mailto:%s"
Test that everything works by starting Chromium, then clicking on a mailto: link, for example the Contact link at the bottom of http://oswatershed.org.
The first time you click the link, Chromium will ask for permission to run the command, so you can check that it is correct. Check the checkbox to have Chromium remember your choice.
Comments and suggestions are very welcome.
Last edited by ackalker (2012-12-04 04:08:32)

Answer 1

The Preferences file has changed since Dec. 2012. The "cloud_print" input has changed. Adding your mod input to the Preferences file induced a Google warning--I undid. It seems that the previous mods prove sufficient. Thanks!
Last edited by rbrband (2014-04-23 20:13:40)