Make it possible to run Sky apps offline

sky/engine/tonic/dart_library_provider.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SKY_ENGINE_TONIC_DART_LIBRARY_PROVIDER_H_
 #define SKY_ENGINE_TONIC_DART_LIBRARY_PROVIDER_H_
 
 #include "base/callback.h"
 #include "dart/runtime/include/dart_api.h"
 #include "mojo/public/cpp/system/data_pipe.h"
 #include "sky/engine/wtf/text/WTFString.h"
 
 namespace blink {
 
+typedef base::Callback<void(mojo::ScopedDataPipeConsumerHandle)>
+    DataPipeConsumerCallback;
+
 class DartLibraryProvider {
  public:
-  virtual void GetLibraryAsStream(
-      const String& name,
-      base::Callback<void(mojo::ScopedDataPipeConsumerHandle)> callback) = 0;
+  virtual void GetLibraryAsStream(const String& name,
+                                  DataPipeConsumerCallback callback) = 0;
 
   virtual Dart_Handle CanonicalizeURL(Dart_Handle library, Dart_Handle url) = 0;
 
- protected:
   virtual ~DartLibraryProvider();
 };
 
 }  // namespace blink
 
 #endif  // SKY_ENGINE_TONIC_DART_LIBRARY_PROVIDER_H_