[s13n] Replace inheritance of PO2TS::Observer by IdentityManager::Observer in AboutSigninInternals

CL is an incremental step to get away from PO2TS from AboutSigninInternals.

BUG=809539

Change-Id: Id8e8baea53c76eedee1bb3ac83f2ccb347909210
Reviewed-on: https://chromium-review.googlesource.com/c/1426760Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#625167}

components/signin/core/browser/about_signin_internals.cc

@@ -302,7 +302,6 @@ void AboutSigninInternals::Initialize(SigninClient* client) {
   signin_error_controller_->AddObserver(this);
   identity_manager_->AddObserver(this);
   identity_manager_->AddDiagnosticsObserver(this);
-  token_service_->AddObserver(this);
   token_service_->AddDiagnosticsObserver(this);
   cookie_manager_service_->AddObserver(this);
 }
@@ -311,7 +310,6 @@ void AboutSigninInternals::Shutdown() {
   signin_error_controller_->RemoveObserver(this);
   identity_manager_->RemoveObserver(this);
   identity_manager_->RemoveDiagnosticsObserver(this);
-  token_service_->RemoveObserver(this);
   token_service_->RemoveDiagnosticsObserver(this);
   cookie_manager_service_->RemoveObserver(this);
 }
@@ -402,7 +400,7 @@ void AboutSigninInternals::OnRefreshTokensLoaded() {
   NotifyObservers();
 }
 
-void AboutSigninInternals::OnEndBatchChanges() {
+void AboutSigninInternals::OnEndBatchOfRefreshTokenStateChanges() {
   NotifyObservers();
 }
 

components/signin/core/browser/about_signin_internals.h

@@ -37,7 +37,6 @@ using TimedSigninStatusValue = std::pair<std::string, std::string>;
 // to propagate to about:signin-internals via SigninInternalsUI.
 class AboutSigninInternals
     : public KeyedService,
-      public OAuth2TokenService::Observer,
       public OAuth2TokenService::DiagnosticsObserver,
       public GaiaCookieManagerService::Observer,
       SigninErrorController::Observer,
@@ -212,11 +211,9 @@ class AboutSigninInternals
   void OnRefreshTokenRevokedFromSource(const std::string& account_id,
                                        const std::string& source) override;
 
-  // OAuth2TokenServiceDelegate::Observer implementations.
-  void OnRefreshTokensLoaded() override;
-  void OnEndBatchChanges() override;
-
   // IdentityManager::Observer implementations.
+  void OnRefreshTokensLoaded() override;
+  void OnEndBatchOfRefreshTokenStateChanges() override;
   void OnPrimaryAccountSigninFailed(
       const GoogleServiceAuthError& error) override;
   void OnPrimaryAccountSet(const AccountInfo& primary_account_info) override;