Use command line to signal whether a child process was passed V8 snapshot files via file descriptor

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index ecac5318e6152270ecda1330fffb4f18ba9b590c..4a10a18bfe95eafdf9c20048e2ff34245cfc0135 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -1203,6 +1203,15 @@ void ChromeContentBrowserClient::AppendExtraCommandLineSwitches(
                                   homedir.value().c_str());
 #endif
 
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+#if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+  if (process_type != switches::kZygoteProcess) {
+    command_line->AppendSwitch(::switches::kV8NativesPassedByFD);
+    command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
+  }
+#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+#endif  // OS_POSIX && !OS_MACOSX
+
   if (process_type == switches::kRendererProcess) {
     content::RenderProcessHost* process =
         content::RenderProcessHost::FromID(child_process_id);