Fix "unused variable" warnings.

components/signin/core/browser/signin_tracker.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_SIGNIN_CORE_BROWSER_SIGNIN_TRACKER_H_
 #define COMPONENTS_SIGNIN_CORE_BROWSER_SIGNIN_TRACKER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "components/signin/core/browser/gaia_cookie_manager_service.h"
 #include "components/signin/core/browser/signin_manager.h"
 #include "google_apis/gaia/google_service_auth_error.h"
 
 class ProfileOAuth2TokenService;
-class SigninClient;
 
 // The signin flow logic is spread across several classes with varying
 // responsibilities:
 //
 // SigninTracker (this class) - This class listens to notifications from various
 // services (SigninManager, OAuth2TokenService) and coalesces them into
 // notifications for the UI layer. This is the class that encapsulates the logic
 // that determines whether a user is fully logged in or not, and exposes
 // callbacks so various pieces of the UI (OneClickSyncStarter) can track the
 // current startup state.
@@ skipping 43 matching lines @@
   };
 
   // Creates a SigninTracker that tracks the signin status on the passed
   // classes, and notifies the |observer| on status changes. All of the
   // instances with the exception of |account_reconcilor| must be non-null and
   // must outlive the SigninTracker. |account_reconcilor| will be used if it is
   // non-null.
   SigninTracker(ProfileOAuth2TokenService* token_service,
                 SigninManagerBase* signin_manager,
                 GaiaCookieManagerService* cookie_manager_service,
-                SigninClient* client,
                 Observer* observer);
   ~SigninTracker() override;
 
   // SigninManagerBase::Observer implementation.
   void GoogleSigninFailed(const GoogleServiceAuthError& error) override;
 
   // OAuth2TokenService::Observer implementation.
   void OnRefreshTokenAvailable(const std::string& account_id) override;
   void OnRefreshTokenRevoked(const std::string& account_id) override;
 
  private:
   // Initializes this by adding notifications and observers.
   void Initialize();
 
   // GaiaCookieManagerService::Observer implementation.
   void OnAddAccountToCookieCompleted(
       const std::string& account_id,
       const GoogleServiceAuthError& error) override;
 
   // The classes whose collective signin status we are tracking.
   ProfileOAuth2TokenService* token_service_;
   SigninManagerBase* signin_manager_;
   GaiaCookieManagerService* cookie_manager_service_;
 
-  // The client associated with this instance.
-  SigninClient* client_;
-
   // Weak pointer to the observer we call when the signin state changes.
   Observer* observer_;
 
   DISALLOW_COPY_AND_ASSIGN(SigninTracker);
 };
 
 #endif  // COMPONENTS_SIGNIN_CORE_BROWSER_SIGNIN_TRACKER_H_