Delete unused code in chrome/common or mark them as platform specific.

chrome/browser/first_run/first_run.cc

Index: chrome/browser/first_run/first_run.cc
diff --git a/chrome/browser/first_run/first_run.cc b/chrome/browser/first_run/first_run.cc
index 26ef116fd0cdab8223853d4757a68aa88bcff183..671799c6b63f690b39e5e9dae48132fa14d70025 100644
--- a/chrome/browser/first_run/first_run.cc
+++ b/chrome/browser/first_run/first_run.cc
@@ -376,9 +376,11 @@ void FirstRunBubbleLauncher::Observe(
   }
 
   if (contents && contents->GetURL().SchemeIs(content::kChromeUIScheme)) {
+#if defined(OS_WIN)
     // Suppress the first run bubble if 'make chrome metro' flow is showing.
     if (contents->GetURL().host() == chrome::kChromeUIMetroFlowHost)
       return;
+#endif
 
     // Suppress the first run bubble if the NTP sync promo bubble is showing
     // or if sign in is in progress.