Add audible support to the copresence API.

components/copresence/proto/data.proto

 syntax = "proto2";
 package copresence;
 option optimize_for = LITE_RUNTIME;
 import "enums.proto";
 import "identity.proto";
 message ClientVersion {
   optional string client = 1;
   optional string version_name = 2;
   optional int64 version_code = 3;
   optional string certificate_fingerprint = 4;
@@ skipping 83 matching lines @@
   optional string id = 1;
   optional AccessPolicy access_policy = 2;
   optional Message message = 3;
   optional TransmissionStrategy strategy = 4;
   optional TokenExchangeStrategy token_exchange_strategy = 5;
   optional OptInStateFilter opt_in_state_filter = 6;
 }
 message TokenExchangeStrategy {
   optional AudioConfiguration audio_configuration = 1;
   optional BroadcastScanConfiguration broadcast_scan_configuration = 2;
+  // TODO(rkc): Horrible hack. Get rid of this once the server tells us whether
+  // or not to use audible for a given publish or subscribe.
+  // http://b/16849245/
+  optional bool use_audible = 99;
 }
 message SubscribedMessage {
   message Debug {
     optional string published_message_id = 1;
     optional string publisher_identity_id = 2;
     optional string publisher_device_id = 3;
     optional int64 creation_timestamp_millis = 4;
     optional int64 ttl_millis = 5;
     optional TransmissionStrategy strategy = 6;
     optional TokenExchangeStrategy token_exchange_strategy = 7;
@@ skipping 24 matching lines @@
 }
 message MessageResult {
   optional string published_message_id = 1;
 }
 message SubscriptionResult {
   optional string subscription_id = 1;
 }
 message OptInStateFilter {
   repeated OptInState allowed_opt_in_state = 1;
 }