It doesn’t work. To make a long story short, I spent 7 hours looking for alternatives and determined a perfect storm to keep me from using Chrome full-time had taken place:

• Processing is built on Java
• Apple disables the Java 6 plugin for all browsers in Mountain Lion
• To use Java in the browser in Mountain Lion, one must download the Java 7 plugin
• Chrome is 32-bit, and thus incompatible with the 64-bit Java 7 plugin
• Safari and Firefox both have 64-bit versions compatible with Java 7
• Processing requires a Java plugin to run in a browser

Conclusion: If I want to go on certain websites that embed processing applets, I cannot use Chrome full-time as my browser anymore.

Edit: Apple Blocks Java 7 Plug-in on OS X to Address Widespread Security Threat, so, I guess just processing.js for me.