Revert of Revert of Inline sign in extracts gaia id from HTTP header and seeds account tracker

chromeos/login/auth/user_context.h

Index: chromeos/login/auth/user_context.h
diff --git a/chromeos/login/auth/user_context.h b/chromeos/login/auth/user_context.h
index ff28c966eba8f2b27a0835fc4182e2723ce0d623..879e59a29b586a952be24216f6d1be84e06afa79 100644
--- a/chromeos/login/auth/user_context.h
+++ b/chromeos/login/auth/user_context.h
@@ -41,6 +41,7 @@
   bool operator!=(const UserContext& context) const;
 
   const std::string& GetUserID() const;
+  const std::string& GetGaiaID() const;
   const Key* GetKey() const;
   Key* GetKey();
   const std::string& GetAuthCode() const;
@@ -54,6 +55,7 @@
   bool HasCredentials() const;
 
   void SetUserID(const std::string& user_id);
+  void SetGaiaID(const std::string& gaia_id);
   void SetKey(const Key& key);
   void SetAuthCode(const std::string& auth_code);
   void SetUserIDHash(const std::string& user_id_hash);
@@ -67,6 +69,7 @@
 
  private:
   std::string user_id_;
+  std::string gaia_id_;
   Key key_;
   std::string auth_code_;
   std::string user_id_hash_;