Infrastructure for reading V8's initial snapshot from external files

gin/shell/gin_main.cc

Index: gin/shell/gin_main.cc
diff --git a/gin/shell/gin_main.cc b/gin/shell/gin_main.cc
index 77b167a43b67af7e517c9a70d3cab0d6b7ba48bf..91152f0ba10cb98818de3c416a0fa17b3c611503 100644
--- a/gin/shell/gin_main.cc
+++ b/gin/shell/gin_main.cc
@@ -61,6 +61,9 @@ int main(int argc, char** argv) {
   base::AtExitManager at_exit;
   CommandLine::Init(argc, argv);
   base::i18n::InitializeICU();
+#ifdef V8_USE_EXTERNAL_STARTUP_DATA
+  gin::IsolateHolder::LoadV8Snapshot();
+#endif
 
   gin::IsolateHolder::Initialize(gin::IsolateHolder::kStrictMode,
                                  gin::ArrayBufferAllocator::SharedInstance());