GcmNetworkManager Class to create apps with robust "send-to-sync", which is the mechanism to sync data with servers where new information is available. 
GcmTaskService Implemented by the client application to provide an endpoint for the GcmNetworkManager to call back to when a task is ready to be executed. 
OneoffTask A task that will execute once,at some point within the specified window. 
OneoffTask.Builder Builder class for constructing OneoffTask objects. 
PeriodicTask A periodic task is one that will recur at the specified interval, without needing to be rescheduled. 
PeriodicTask.Builder Builder class for constructing PeriodicTask objects. 
Task Encapsulates the parameters of a task that you will schedule on the GcmNetworkManager
Task.Builder Builder object to construct these tasks before sending them to the network manager. 
TaskParams Container of parameters handed off to the client app in onRunTask(TaskParams)