Chrome needs special handling because of strange OfflineAudioContext's behavior: while Firefox calls onaudioprocess 10 times per every second of audio buffer, Chrome calls it 2 (or 1) times for the whole audio no matter how long it is. Here is small JSFiddle to demonstrate it:
http://jsfiddle.net/95EBf/4/
For this reason I split audio buffer to small samples (0.1 second each) and process each separately in Chrome. Probably this workaround should be separated from "standard" implementation for better readability, what do you think?