Fixes for -Wunused-function on Linux, Android and ChromeOS

chrome/browser/ui/auto_login_prompter.cc

Index: chrome/browser/ui/auto_login_prompter.cc
diff --git a/chrome/browser/ui/auto_login_prompter.cc b/chrome/browser/ui/auto_login_prompter.cc
index 70311db135a30bb0a1e14e8b28d85fdb178282fd..30f1ed82a9bb4f52fa05167135421a964a0ad376 100644
--- a/chrome/browser/ui/auto_login_prompter.cc
+++ b/chrome/browser/ui/auto_login_prompter.cc
@@ -29,6 +29,7 @@ using content::WebContents;
 
 namespace {
 
+#if !defined(OS_ANDROID)
 bool FetchUsernameThroughSigninManager(Profile* profile, std::string* output) {
   // In an incognito window these services are not available.
   SigninManagerBase* signin_manager =
@@ -46,6 +47,7 @@ bool FetchUsernameThroughSigninManager(Profile* profile, std::string* output) {
   *output = signin_manager->GetAuthenticatedUsername();
   return true;
 }
+#endif  // !defined(OS_ANDROID)
 
 }  // namespace