Implement |RevokeCredentials| and |RevokeAllCredentials| in CrOSO2TSDelegate

The implementations are |NOTREACHED()| since users cannnot sign out of
Chrome in Chrome OS.

Bug: 820046
Change-Id: Ie559d52388418d5a8a182afdb8a08f92b726c21b
Reviewed-on: https://chromium-review.googlesource.com/1076291Reviewed-by: Lutz Justen <ljusten@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Kush Sinha <sinhak@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563076}

chrome/browser/chromeos/oauth2_token_service_delegate.cc

@@ -230,4 +230,15 @@ void ChromeOSOAuth2TokenServiceDelegate::OnTokenUpserted(
   }
 }
 
+void ChromeOSOAuth2TokenServiceDelegate::RevokeCredentials(
+    const std::string& account_id) {
+  // Signing out of Chrome is not possible on Chrome OS.
+  NOTREACHED();
+}
+
+void ChromeOSOAuth2TokenServiceDelegate::RevokeAllCredentials() {
+  // Signing out of Chrome is not possible on Chrome OS.
+  NOTREACHED();
+}
+
 }  // namespace chromeos

chrome/browser/chromeos/oauth2_token_service_delegate.h

@@ -48,12 +48,12 @@ class ChromeOSOAuth2TokenServiceDelegate : public OAuth2TokenServiceDelegate,
                          const std::string& refresh_token) override;
   net::URLRequestContextGetter* GetRequestContext() const override;
   LoadCredentialsState GetLoadCredentialsState() const override;
+  void RevokeCredentials(const std::string& account_id) override;
+  void RevokeAllCredentials() override;
 
   // |AccountManager::Observer| overrides
   void OnTokenUpserted(const AccountManager::AccountKey& account_key) override;
 
-  // TODO(sinhak): Implement server token revocation.
-
  private:
   // Callback handler for |AccountManager::GetAccounts|.
   void GetAccountsCallback(