New event listeners and new event types

This is a first step towards moving ChangeHooks into a plugin.  The
listeners[1] are now invoked from all places where corresponding
hooks are invoked.  Invocation of hooks is not removed in this change.
This will happen when we make sure that they are invoked from a new
event listener.

[1] All listeners under:
gerrit-extension-api/src/main/java/com/google/gerrit/extensions/events/

Change-Id: I6e5356edb2c326d2d7a0133b84509ad6071140d0

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/account/AccountSecurityImpl.java

@@ -33,6 +33,7 @@ import com.google.gerrit.server.account.AccountByEmailCache;
 import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.GroupCache;
 import com.google.gerrit.server.account.Realm;
+import com.google.gerrit.server.extensions.events.AgreementSignup;
 import com.google.gerrit.server.project.ProjectCache;
 import com.google.gwtjsonrpc.common.AsyncCallback;
 import com.google.gwtjsonrpc.common.VoidResult;
@@ -58,6 +59,7 @@ class AccountSecurityImpl extends BaseServiceImplementation implements
   private final ChangeHooks hooks;
   private final GroupCache groupCache;
   private final AuditService auditService;
+  private final AgreementSignup agreementSignup;
 
   @Inject
   AccountSecurityImpl(final Provider<ReviewDb> schema,
@@ -68,7 +70,8 @@ class AccountSecurityImpl extends BaseServiceImplementation implements
       final DeleteExternalIds.Factory deleteExternalIdsFactory,
       final ExternalIdDetailFactory.Factory externalIdDetailFactory,
       final ChangeHooks hooks, final GroupCache groupCache,
-      final AuditService auditService) {
+      final AuditService auditService,
+      AgreementSignup agreementSignup) {
     super(schema, currentUser);
     realm = r;
     user = u;
@@ -80,6 +83,7 @@ class AccountSecurityImpl extends BaseServiceImplementation implements
     this.externalIdDetailFactory = externalIdDetailFactory;
     this.hooks = hooks;
     this.groupCache = groupCache;
+    this.agreementSignup = agreementSignup;
   }
 
   @Override
@@ -153,6 +157,7 @@ class AccountSecurityImpl extends BaseServiceImplementation implements
         }
 
         Account account = user.get().getAccount();
+        agreementSignup.fire(account, ca.getName());
         hooks.doClaSignupHook(account, ca.getName());
 
         final AccountGroupMember.Key key =