Merge "Document that emergency numbers will not be blocked by the platform." into nyc-dev

 * <p>

 * The content provider exposes a table containing blocked numbers. The columns and URIs for

 * accessing this table are defined by the {@link BlockedNumbers} class. Messages, and calls from

 * blocked numbers are discarded by the platform. If the user contacts emergency

 * services, number blocking is disabled by the platform for a duration defined by

 * blocked numbers are discarded by the platform. Notifications upon provider changes can be

 * received using a {@link android.database.ContentObserver}.

 * </p>

 * <p>

 * The platform will not block messages, and calls from emergency numbers as defined by

 * {@link android.telephony.PhoneNumberUtils#isEmergencyNumber(String)}. If the user contacts

 * emergency services, number blocking is disabled by the platform for a duration defined by

 * {@link android.telephony.CarrierConfigManager#KEY_DURATION_BLOCKING_DISABLED_AFTER_EMERGENCY_INT}.

 * Notifications upon provider changes can be received using a

 * {@link android.database.ContentObserver}.

 * </p>

 *

 * <h3> Permissions </h3>