If your Chrome apps or extensions are using cloud messaging capabilities offered by the chrome.pushMessaging API, this email is directed at you. The
chrome.pushMessaging API is now deprecated. To continue using cloud messaging capabilities in your Chrome apps and extensions, please upgrade to the
chrome.gcm API.
The new API offers improvements such as no quota, a backend shared with Android clients, and extra capabilities, including upstream messaging to the server. You can find the schedule for phasing out the deprecated API, as well as resources for upgrading your Chrome apps and extensions, in our chrome.pushMessaging deprecation
blog post.