XdsBootstrap: move two more methods out of the interface (#30820)

* XdsBootstrap: move two more methods out of the interface

* Automated change: Fix sanity tests

Co-authored-by: markdroth <markdroth@users.noreply.github.com>

src/core/ext/filters/client_channel/resolver/xds/xds_resolver.cc

@@ -56,6 +56,7 @@
 #include "src/core/ext/filters/client_channel/config_selector.h"
 #include "src/core/ext/filters/client_channel/lb_policy/ring_hash/ring_hash.h"
 #include "src/core/ext/xds/xds_bootstrap.h"
+#include "src/core/ext/xds/xds_bootstrap_grpc.h"
 #include "src/core/ext/xds/xds_client.h"
 #include "src/core/ext/xds/xds_client_grpc.h"
 #include "src/core/ext/xds/xds_http_filters.h"
@@ -838,7 +839,7 @@ void XdsResolver::StartLocked() {
   } else {
     // target_uri.authority not set
     absl::string_view name_template =
-        xds_client_->bootstrap()
+        static_cast<const GrpcXdsBootstrap&>(xds_client_->bootstrap())
             .client_default_listener_resource_name_template();
     if (name_template.empty()) {
       name_template = "%s";

src/core/ext/xds/xds_bootstrap.h

@@ -87,9 +87,6 @@ class XdsBootstrap {
   // add support for fallback for the xds channel.
   virtual const XdsServer& server() const = 0;
   virtual const Node* node() const = 0;
-  virtual const std::string& client_default_listener_resource_name_template()
-      const = 0;
-  virtual const std::string& server_listener_resource_name_template() const = 0;
   virtual const std::map<std::string, Authority>& authorities() const = 0;
 
   // Returns a pointer to the specified authority, or null if it does

src/core/ext/xds/xds_bootstrap_grpc.h

@@ -67,17 +67,16 @@ class GrpcXdsBootstrap : public XdsBootstrap {
 
   const XdsServer& server() const override { return servers_[0]; }
   const Node* node() const override { return node_.get(); }
-  const std::string& client_default_listener_resource_name_template()
-      const override {
-    return client_default_listener_resource_name_template_;
-  }
-  const std::string& server_listener_resource_name_template() const override {
-    return server_listener_resource_name_template_;
-  }
   const std::map<std::string, Authority>& authorities() const override {
     return authorities_;
   }
 
+  const std::string& client_default_listener_resource_name_template() const {
+    return client_default_listener_resource_name_template_;
+  }
+  const std::string& server_listener_resource_name_template() const {
+    return server_listener_resource_name_template_;
+  }
   const XdsCertificateProviderPluginMapInterface*
   certificate_provider_plugin_map() const {
     return certificate_provider_plugin_map_.get();

src/core/ext/xds/xds_server_config_fetcher.cc

@@ -51,7 +51,7 @@
 #include "src/core/ext/filters/server_config_selector/server_config_selector.h"
 #include "src/core/ext/filters/server_config_selector/server_config_selector_filter.h"
 #include "src/core/ext/xds/certificate_provider_store.h"
-#include "src/core/ext/xds/xds_bootstrap.h"
+#include "src/core/ext/xds/xds_bootstrap_grpc.h"
 #include "src/core/ext/xds/xds_certificate_provider.h"
 #include "src/core/ext/xds/xds_channel_stack_modifier.h"
 #include "src/core/ext/xds/xds_client_grpc.h"
@@ -502,7 +502,8 @@ void XdsServerConfigFetcher::StartWatch(
   XdsListenerResourceType::StartWatch(
       xds_client_.get(),
       ListenerResourceName(
-          xds_client_->bootstrap().server_listener_resource_name_template(),
+          static_cast<const GrpcXdsBootstrap&>(xds_client_->bootstrap())
+              .server_listener_resource_name_template(),
           listening_address),
       std::move(listener_watcher));
   MutexLock lock(&mu_);
@@ -518,7 +519,8 @@ void XdsServerConfigFetcher::CancelWatch(
     XdsListenerResourceType::CancelWatch(
         xds_client_.get(),
         ListenerResourceName(
-            xds_client_->bootstrap().server_listener_resource_name_template(),
+            static_cast<const GrpcXdsBootstrap&>(xds_client_->bootstrap())
+                .server_listener_resource_name_template(),
             it->second->listening_address()),
         it->second, false /* delay_unsubscription */);
     listener_watchers_.erase(it);
@@ -1344,8 +1346,8 @@ grpc_server_config_fetcher* grpc_server_config_fetcher_xds_create(
             xds_client.status().ToString().c_str());
     return nullptr;
   }
-  if ((*xds_client)
+  if (static_cast<const grpc_core::GrpcXdsBootstrap&>(
-          ->bootstrap()
+          (*xds_client)->bootstrap())
           .server_listener_resource_name_template()
           .empty()) {
     gpr_log(GPR_ERROR,