Factor out snapshot helpers from main.cc.

runtime/bin/snapshot_utils.h

+// Copyright (c) 2017, 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 RUNTIME_BIN_SNAPSHOT_UTILS_H_
+#define RUNTIME_BIN_SNAPSHOT_UTILS_H_
+
+#include "platform/globals.h"
+
+namespace dart {
+namespace bin {
+
+class Snapshot {
+ public:
+  static void GenerateScript(const char* snapshot_filename);
+  static void GenerateAppJIT(const char* snapshot_filename);
+  static void GenerateAppAOTAsBlobs(const char* snapshot_filename);
+  static void GenerateAppAOTAsAssembly(const char* snapshot_filename);
+
+  static bool ReadAppSnapshot(const char* script_name,
+                              const uint8_t** vm_data_buffer,
+                              const uint8_t** vm_instructions_buffer,
+                              const uint8_t** isolate_data_buffer,
+                              const uint8_t** isolate_instructions_buffer);
+
+ private:
+  DISALLOW_ALLOCATION();
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Snapshot);
+};
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // RUNTIME_BIN_SNAPSHOT_UTILS_H_