Use Provider to obtain LifecycleListeners

Instead of holding onto a singleton for a LifecycleListener, allow the
listener to be created on demand using a Provider.

Use explicit support of the HandlerRegistration type, enabling these
to always be cleared before any LifecycleListener is stopped. This way
registrations from plugins can always be cleared even if the list of
listeners to start didn't finish running to the end.

During stop only run those listeners that attempted to start. We
assume a listener is prepared to run its stop method as soon as its
start method begins execution. This means a start method that can fail
must use guards in its stop method to handle stopping after a partial
start failure.

Change-Id: I86ae39a51e3b7fad5c5af445bf7c70133222c31a

gerrit-server/src/main/java/com/google/gerrit/server/plugins/Plugin.java

@@ -20,7 +20,6 @@ import com.google.gerrit.extensions.annotations.PluginData;
 import com.google.gerrit.extensions.annotations.PluginName;
 import com.google.gerrit.extensions.registration.RegistrationHandle;
 import com.google.gerrit.extensions.registration.ReloadableRegistrationHandle;
-import com.google.gerrit.lifecycle.LifecycleListener;
 import com.google.gerrit.lifecycle.LifecycleManager;
 import com.google.inject.AbstractModule;
 import com.google.inject.Guice;
@@ -233,28 +232,14 @@ public class Plugin {
     return httpInjector;
   }
 
-  public void add(final RegistrationHandle handle) {
+  public void add(RegistrationHandle handle) {
     if (handle instanceof ReloadableRegistrationHandle) {
       if (reloadableHandles == null) {
         reloadableHandles = Lists.newArrayList();
       }
       reloadableHandles.add((ReloadableRegistrationHandle<?>) handle);
     }
-
-    add(new LifecycleListener() {
-      @Override
-      public void start() {
-      }
-
-      @Override
-      public void stop() {
-        handle.remove();
-      }
-    });
-  }
-
-  public void add(LifecycleListener listener) {
-    manager.add(listener);
+    manager.add(handle);
   }
 
   List<ReloadableRegistrationHandle<?>> getReloadableHandles() {