Add immutable methods withGrpcCallOption, withMetadata to grpc.web.request, response

Author: stanley-cheung

javascript/net/grpc/web/request.js

@@ -40,6 +40,21 @@ class Request {
    * @return {!CallOptions|undefined}
    */
   getCallOptions() {}
+
+   /**
+   * @param {string} key
+   * @param {string} value
+   * @return {!Request<REQUEST, RESPONSE>}
+   */
+  withMetadata(key, value) {}
+
+  /**
+   * @param {string} name
+   * @param {VALUE} value
+   * @template VALUE
+   * @return {!Request<REQUEST, RESPONSE>}
+   */
+  withGrpcCallOption(name, value) {}
 }
 
 exports = Request;

javascript/net/grpc/web/requestinternal.js

@@ -73,6 +73,22 @@ class RequestInternal {
   getCallOptions() {
     return this.callOptions_;
   }
+
+  /**
+   * @override
+   */
+  withMetadata(key, value) {
+    this.metadata_[key] = value;
+    return this;
+  }
+
+  /**
+   * @override
+   */
+  withGrpcCallOption(name, value) {
+    this.callOptions_.setOption(name, value);
+    return this;
+  }
 }
 
 exports = RequestInternal;