health_check: move service_name into HttpHealthCheck. (#117)

This is really quite HTTP specific.

api/health_check.proto

@@ -29,15 +29,6 @@ message HealthCheck {
   // Reuse health check connection between health checks. Default is true.
   google.protobuf.BoolValue reuse_connection = 7;
 
-  // The Envoy HTTP health checker supports the service_name option. If this
-  // option is set, the health checker additionally compares the value of the
-  // x-envoy-upstream-healthchecked-cluster response header to service_name. If
-  // the values do not match, the health check does not pass. The upstream
-  // health check filter appends x-envoy-upstream-healthchecked-cluster to the
-  // response headers. The appended value is determined by the --service-cluster
-  // command line option.
-  string service_name = 8;
-
   // Describes the encoding of the payload bytes in the payload
   message Payload {
     oneof payload {
@@ -55,6 +46,14 @@ message HealthCheck {
     string path = 2;
     Payload send = 3;
     Payload receive = 4;
+    // The Envoy HTTP health checker supports the service_name option. If this
+    // option is set, the health checker additionally compares the value of the
+    // x-envoy-upstream-healthchecked-cluster response header to service_name. If
+    // the values do not match, the health check does not pass. The upstream
+    // health check filter appends x-envoy-upstream-healthchecked-cluster to the
+    // response headers. The appended value is determined by the --service-cluster
+    // command line option.
+    string service_name = 5;
   }
   message TcpHealthCheck {
     // Empty payloads imply a connect-only health check.
@@ -67,9 +66,9 @@ message HealthCheck {
   message RedisHealthCheck {
   }
   oneof health_checker {
-    HttpHealthCheck http_health_check = 9;
-    TcpHealthCheck tcp_health_check = 10;
-    RedisHealthCheck redis_health_check = 11;
+    HttpHealthCheck http_health_check = 8;
+    TcpHealthCheck tcp_health_check = 9;
+    RedisHealthCheck redis_health_check = 10;
   }
 }