Nothing, sort of. Subject to "Section 1.7 Modifications" of Terms:
b. To the Agreement:
Google may make changes to this Agreement, including pricing (and any linked documents) from time to time.
....
Google will provide at least 90 days’ advance notice for materially adverse changes to any SLAs by either: (i) sending an email to Customer’s primary point of contact; (ii) posting a notice in the Admin Console; or (iii) posting a notice to the applicable SLA webpage. If Customer does not agree to the revised Agreement, please stop using the Services. Google will post any modification to this Agreement to the Terms URL.
b. To the Agreement:
Google may make changes to this Agreement, including pricing (and any linked documents) from time to time. .... Google will provide at least 90 days’ advance notice for materially adverse changes to any SLAs by either: (i) sending an email to Customer’s primary point of contact; (ii) posting a notice in the Admin Console; or (iii) posting a notice to the applicable SLA webpage. If Customer does not agree to the revised Agreement, please stop using the Services. Google will post any modification to this Agreement to the Terms URL.