Move V8 snapshot loading code from isolate_holder to gin/v8_startup_data.{h,cc}.

gin/v8_startup_data.h

+// Copyright 2013 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 GIN_V8_STARTUP_DATA_H_
+#define GIN_V8_STARTUP_DATA_H_
+
+#include "base/files/file.h"
+#include "gin/gin_export.h"
+
+namespace gin {
+
+class GIN_EXPORT V8StartupData {
+ public:
+  static const int kV8SnapshotBasePathKey;
+  static const char kNativesFileName[];
+  static const char kSnapshotFileName[];
+
+  static void GetV8ExternalSnapshotData(const char** natives_data_out,
+                                        int* natives_size_out,
+                                        const char** snapshot_data_out,
+                                        int* snapshot_size_out);
+
+#if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+
+  static bool LoadV8SnapshotFromFile(base::PlatformFile natives_fd,
+                                     int64 natives_offset,
+                                     int64 natives_size,
+                                     base::PlatformFile snapshot_fd,
+                                     int64 snapshot_offset,
+                                     int64 snapshot_size);
+
+  static bool LoadV8Snapshot();
+
+#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+
+  static void Initialize();
+};
+
+}  // namespace gin
+
+#endif  // GIN_V8_STARTUP_DATA_H_