We already have the possibility to use Google Voice search in Navigator, which is very nice. On my phone I did not use it very often as the buttons are quite small, but on my new 8" android head unit it is different.
It would be nice though if Navigator would be integrated with OK Google from the Google app, which needs to be on your device anyway if you want to use voice search.
This could be outside Navigator with "OK Google, Search [Eiffel Tower Paris] on [Navigator]". The square brackets are typed to display the command structure.
However, currently it only works if your phone/tablet/car head unit is set to English.
Inside Navigator it could work the same with the OK Google integration.
I'm not a java programmer at all so I could be completely wrong, but from what I read from the documentation is that when you already have a (google) search intent/filter, you only need to add the following two lines to the <intent-filter /> tag of the Activity in the manifest.
And then you could say inside Navigator something like "OK Google, Search [Big Ben London]"
If it is really that simple (and I hope it is :) ), could you give that a try?
Currently I can use "OK Google, Start Navigator" if I set my device to English, or do that from the google voice widget when set on default Dutch. It's funny but not yet as useful as simply tapping the shortcut on the home screen.
It gets useful when it would work inside Navigator without having to tap the "microphone" button and then the "search" button (although I'm happy with that as well. I can't think of another Nav app having that.)