Remove BrowserSignin, as it's not used anywhere.

chrome/browser/profiles/profile_impl.cc

Index: chrome/browser/profiles/profile_impl.cc
diff --git a/chrome/browser/profiles/profile_impl.cc b/chrome/browser/profiles/profile_impl.cc
index d33e81a0ff905070e93320a1b8be35bf3c0d1466..7870c2b8d4403ad6c62a01d797a88d7991baa441 100644
--- a/chrome/browser/profiles/profile_impl.cc
+++ b/chrome/browser/profiles/profile_impl.cc
@@ -20,7 +20,6 @@
 #include "chrome/browser/background/background_mode_manager.h"
 #include "chrome/browser/bookmarks/bookmark_model.h"
 #include "chrome/browser/browser_process.h"
-#include "chrome/browser/browser_signin.h"
 #include "chrome/browser/browsing_data_remover.h"
 #include "chrome/browser/content_settings/host_content_settings_map.h"
 #include "chrome/browser/custom_handlers/protocol_handler_registry.h"
@@ -1544,13 +1543,6 @@ ProfileSyncService* ProfileImpl::GetProfileSyncService(
   return sync_service_.get();
 }
 
-BrowserSignin* ProfileImpl::GetBrowserSignin() {
-  if (!browser_signin_.get()) {
-    browser_signin_.reset(new BrowserSignin(this));
-  }
-  return browser_signin_.get();
-}
-
 void ProfileImpl::InitSyncService(const std::string& cros_user) {
   profile_sync_factory_.reset(
       new ProfileSyncFactoryImpl(this, CommandLine::ForCurrentProcess()));