Add WARN_UNUSED_RESULT to bool EmbeddedTestServer::Start()

net/test/embedded_test_server/embedded_test_server.h

Index: net/test/embedded_test_server/embedded_test_server.h
diff --git a/net/test/embedded_test_server/embedded_test_server.h b/net/test/embedded_test_server/embedded_test_server.h
index a1f5d253ac802aeec53ca74bf91614d8066a5121..e3065c0f56ae6c8d36e002ea77187323149ddbe7 100644
--- a/net/test/embedded_test_server/embedded_test_server.h
+++ b/net/test/embedded_test_server/embedded_test_server.h
@@ -133,7 +133,7 @@ class EmbeddedTestServer {
   // This is the equivalent of calling InitializeAndListen() followed by
   // StartAcceptingConnections().
   // Returns whether a listening socket has been successfully created.
-  bool Start();
+  bool Start() WARN_UNUSED_RESULT;
 
   // Starts listening for incoming connections but will not yet accept them.
   // Returns whether a listening socket has been succesfully created.