Changed AuthManager::CreateAccessToken and AuthManager::ParseAccessToken

With this API we can handle expiration checks inside of AuthManager

BUG=25768507

Change-Id: I2fa5d428be6f0772d8b2656eb2bee71824f0d308
Reviewed-on: https://weave-review.googlesource.com/2030
Reviewed-by: Vitaly Buka <vitalybuka@google.com>
diff --git a/src/privet/auth_manager.h b/src/privet/auth_manager.h
index a74e43b..8b99254 100644
--- a/src/privet/auth_manager.h
+++ b/src/privet/auth_manager.h
@@ -33,9 +33,12 @@
               base::Clock* clock = nullptr);
   ~AuthManager();
 
-  std::vector<uint8_t> CreateAccessToken(const UserInfo& user_info);
-  UserInfo ParseAccessToken(const std::vector<uint8_t>& token,
-                            base::Time* time) const;
+  std::vector<uint8_t> CreateAccessToken(const UserInfo& user_info,
+                                         base::TimeDelta ttl) const;
+
+  bool ParseAccessToken(const std::vector<uint8_t>& token,
+                        UserInfo* user_info,
+                        ErrorPtr* error) const;
 
   const std::vector<uint8_t>& GetSecret() const { return secret_; }
   const std::vector<uint8_t>& GetCertificateFingerprint() const {