Add patch file support to Dart embedder

mojo/dart/embedder/builtin.h

 // Copyright 2014 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 MOJO_DART_EMBEDDER_BUILTIN_H_
 #define MOJO_DART_EMBEDDER_BUILTIN_H_
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 15 matching lines @@
   // the builtin_libraries_ array in builtin.cc.
   enum BuiltinLibraryId {
     kBuiltinLibrary = 0,
     kMojoBindingsLibrary = 1,
     kMojoCoreLibrary = 2,
     kInvalidLibrary,
   };
 
   static uint8_t snapshot_magic_number[4];
 
-  static void SetNativeResolver(BuiltinLibraryId id);
+  // Return the library specified in 'id'.
+  static Dart_Handle GetLibrary(BuiltinLibraryId id);
 
-  // Check if built in library specified in 'id' is already loaded, if not
-  // load it.
-  static Dart_Handle LoadAndCheckLibrary(BuiltinLibraryId id);
+  // Prepare the library specified in 'id'. Preparation includes:
+  // 1) Setting the native resolver (if any).
+  // 2) Applying patch files (if any).
+  // NOTE: This should only be called once for a library per isolate.
+  static void PrepareLibrary(BuiltinLibraryId id);
 
   static int64_t GetIntegerValue(Dart_Handle value_obj) {
     int64_t value = 0;
     Dart_Handle result = Dart_IntegerToInt64(value_obj, &value);
     if (Dart_IsError(result))
       Dart_PropagateError(result);
     return value;
   }
 
   static Dart_Handle NewError(const char* format, ...);
 
  private:
   // Native method support.
   static Dart_NativeFunction NativeLookup(Dart_Handle name,
                                           int argument_count,
                                           bool* auto_setup_scope);
 
   static const uint8_t* NativeSymbol(Dart_NativeFunction nf);
-
+  static Dart_Handle GetStringResource(const char* resource_name);
+  static void LoadPatchFiles(Dart_Handle library,
+                             const char* patch_uri,
+                             const char** patch_files);
   typedef struct {
     const char* url_;
     bool has_natives_;
     Dart_NativeEntrySymbol native_symbol_;
     Dart_NativeEntryResolver native_resolver_;
+    const char* patch_url_;
+    const char** patch_resources_;
   } builtin_lib_props;
   static builtin_lib_props builtin_libraries_[];
 
+  static const char* mojo_core_patch_resource_names_[];
   DISALLOW_IMPLICIT_CONSTRUCTORS(Builtin);
 };
 
 }  // namespace dart
 }  // namespace mojo
 
 #endif  // MOJO_DART_EMBEDDER_BUILTIN_H_