If the Google ebook is the dictionary, then this isn't sufficient. This is because MOBI dictionaries have a spacial format, typically only available via MobiPocket Creator. See How to create your own mobipocket dictionary for any language:
. Even closer to your needs is Converting Encarta Dictionaries to Mobipocket Tutorial
, since this starts with a conventional ebook dictionary and makes it into a searchable dictionary.
You may be better off looking for a freely available StarDict (say) dictionary as the starting point, but if starting from a Google ebook the best version would be the ePub which is only available from Sony.