Add App Usage atom to atoms.proto

            266 [(module) = "framework"];

        AccessibilityServiceReported accessibility_service_reported = 267 [(module) = "settings"];

        DocsUIDragAndDropReported docs_ui_drag_and_drop_reported = 268 [(module) = "docsui"];

        AppUsageEventOccurred app_usage_event_occurred = 269 [(module) = "framework"];

        SdkExtensionStatus sdk_extension_status = 354;

        // StatsdStats tracks platform atoms with ids upto 500.

    optional android.stats.accessibility.ServiceStatus service_status = 2;

}

message DisplayWakeReason {

    // Wake_up_reason code

    // If LOWORD(wake_up_reason) = 0

    // Count of wake up by reason

    optional int32 wake_times = 2;

}

/**

 * Logs app usage events.

 */

message AppUsageEventOccurred {

    optional int32 uid = 1;

    optional string package_name = 2;

    optional string class_name = 3;

    enum EventType {

        NONE = 0;

        MOVE_TO_FOREGROUND = 1;

        MOVE_TO_BACKGROUND = 2;

    }

    optional EventType event_type = 4;

}