Support Sync following Gaia OAuth authentication

chrome/browser/sync/signin_manager.h

Index: chrome/browser/sync/signin_manager.h
diff --git a/chrome/browser/sync/signin_manager.h b/chrome/browser/sync/signin_manager.h
index 879fe484c300a287de3c520db41c7c70a6b99cbe..ce6ba2961ead3de33f14a6a8e336c7fca6303659 100644
--- a/chrome/browser/sync/signin_manager.h
+++ b/chrome/browser/sync/signin_manager.h
@@ -116,12 +116,18 @@ class SigninManager : public GaiaAuthConsumer,
 
  private:
   void PrepareForSignin();
+  void PrepareForOAuthSignin();
 
   Profile* profile_;
+
+  // ClientLogin identity.
   std::string username_;
   std::string password_;  // This is kept empty whenever possible.
   bool had_two_factor_error_;
 
+  // OAuth identity.
+  std::string oauth_username_;
+
   void CleanupNotificationRegistration();
 
   // Result of the last client login, kept pending the lookup of the