Compared to a lot of API providers which may changes APIs without notice, Google tries to notice it at least 7 days before. I did not see non respected one in my search, on google ;)
from https://developers.google.com/terms/
"Changes are effective seven (7) days after they are posted. However, changes specific to new functionality for an API or changes made for legal reasons will be effective immediately. You agree that your continued use of the API constitutes an acceptance of the modified terms."