API update for "Remove unused OAuthToken..."

Update the classes to reflect the API change introduced in commit 3408d4deb866,
which changed the OAuthServiceProvider interface.
diff --git a/src/main/java/com/googlesource/gerrit/plugins/oauth/GitHubOAuthService.java b/src/main/java/com/googlesource/gerrit/plugins/oauth/GitHubOAuthService.java
index e55b2a2..02f623e 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/oauth/GitHubOAuthService.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/oauth/GitHubOAuthService.java
@@ -69,11 +69,6 @@
   }
 
   @Override
-  public OAuthToken getRequestToken() {
-    throw new IllegalStateException();
-  }
-
-  @Override
   public OAuthUserInfo getUserInfo(OAuthToken token) throws IOException {
     OAuthRequest request = new OAuthRequest(Verb.GET, PROTECTED_RESOURCE_URL);
     Token t =
@@ -105,26 +100,17 @@
   }
 
   @Override
-  public OAuthToken getAccessToken(OAuthToken rt,
-      OAuthVerifier rv) {
-    Token ti = null;
-    if (rt != null) {
-      ti = new Token(rt.getToken(), rt.getSecret(), rt.getRaw());
-    }
+  public OAuthToken getAccessToken(OAuthVerifier rv) {
     Verifier vi = new Verifier(rv.getValue());
-    Token to = service.getAccessToken(ti, vi);
+    Token to = service.getAccessToken(null, vi);
     OAuthToken result = new OAuthToken(to.getToken(),
         to.getSecret(), to.getRawResponse());
     return result;
   }
 
   @Override
-  public String getAuthorizationUrl(OAuthToken rt) {
-    Token ti = null;
-    if (rt != null) {
-      ti = new Token(rt.getToken(), rt.getSecret(), rt.getRaw());
-    }
-    return service.getAuthorizationUrl(ti);
+  public String getAuthorizationUrl() {
+    return service.getAuthorizationUrl(null);
   }
 
   @Override
diff --git a/src/main/java/com/googlesource/gerrit/plugins/oauth/GoogleOAuthService.java b/src/main/java/com/googlesource/gerrit/plugins/oauth/GoogleOAuthService.java
index 65f8541..85a812a 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/oauth/GoogleOAuthService.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/oauth/GoogleOAuthService.java
@@ -92,11 +92,6 @@
   }
 
   @Override
-  public OAuthToken getRequestToken() {
-    throw new IllegalStateException("Not supported workflow in OAuth 2.0");
-  }
-
-  @Override
   public OAuthUserInfo getUserInfo(OAuthToken token) throws IOException {
     OAuthRequest request = new OAuthRequest(Verb.GET, PROTECTED_RESOURCE_URL);
     Token t =
@@ -183,27 +178,17 @@
   }
 
   @Override
-  public OAuthToken getAccessToken(OAuthToken rt,
-      OAuthVerifier rv) {
-    Token ti = null;
-    if (rt != null) {
-      ti = new Token(rt.getToken(), rt.getSecret(), rt.getRaw());
-    }
+  public OAuthToken getAccessToken(OAuthVerifier rv) {
     Verifier vi = new Verifier(rv.getValue());
-    Token to = service.getAccessToken(ti, vi);
+    Token to = service.getAccessToken(null, vi);
     OAuthToken result = new OAuthToken(to.getToken(),
         to.getSecret(), to.getRawResponse());
      return result;
   }
 
   @Override
-  public String getAuthorizationUrl(OAuthToken rt) {
-    Token ti = null;
-    if (rt != null) {
-      ti = new Token(rt.getToken(), rt.getSecret(), rt.getRaw());
-    }
-
-    String url = service.getAuthorizationUrl(ti);
+  public String getAuthorizationUrl() {
+    String url = service.getAuthorizationUrl(null);
     try {
       if (linkToExistingOpenIDAccounts) {
         url += "&openid.realm=" + URLEncoder.encode(canonicalWebUrl,