Support loading dart-ext from within a package when using a package map

runtime/bin/loader.h

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef BIN_LOADER_H_
 #define BIN_LOADER_H_
 
 #include "bin/isolate_data.h"
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
@@ skipping 66 matching lines @@
   intptr_t results_length() {
     return *static_cast<volatile intptr_t*>(&results_length_);
   }
 
   // Send the loader init request to the service isolate.
   void Init(const char* package_root,
             const char* packages_file,
             const char* working_directory,
             const char* root_script_uri);
 
+  // Send a request for a dart-ext: import to the service isolate.
+  void SendImportExtensionRequest(Dart_Handle url,
+                                  Dart_Handle library_url);
+
   // Send a request from the tag handler to the service isolate.
   void SendRequest(Dart_LibraryTag tag,
                    Dart_Handle url,
                    Dart_Handle library_url);
 
   /// Queue |message| and notify the loader that a message is available.
   void QueueMessage(Dart_CObject* message);
 
   /// Blocks the caller until the loader is finished.
   void BlockUntilComplete(ProcessResult process_result);
@@ skipping 38 matching lines @@
 
   // This is the global callback for the native message handlers.
   static void NativeMessageHandler(Dart_Port dest_port_id,
                                    Dart_CObject* message);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_LOADER_H_