Allow RestApiView<RevisionResource> to add buttons on patch sets

RestApiViews that accept a RevisionResource may now also describe
buttons that should appear on a patch set. Description is given to
Gerrit by implementing the UiCommand interface and returning useful
information from the getter methods.

Change-Id: I2b9445e73448968f1e3234812cc28b57e9ec7250

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/webui/UiCommand.java

@@ -0,0 +1,30 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.extensions.webui;
+
+import com.google.gerrit.extensions.restapi.RestResource;
+import com.google.gerrit.extensions.restapi.RestView;
+
+public interface UiCommand<R extends RestResource> extends RestView<R> {
+  public static enum Place {
+    PATCHSET_ACTION_PANEL;
+  };
+
+  Place getPlace();
+  String getLabel(R resource);
+  String getTitle(R resource);
+  boolean isVisible(R resource);
+  boolean isEnabled(R resource);
+}