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 aa9f2b5ea93625067949cad9f40847da0d0caa72..dd3d7581fb093ca04acebd75c565ee7cc3bdb652 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());