Merge changes from topic 'plugin-api'

* changes:
  ServerInfoIT: Use API to install plugin
  Add implementation of PluginApi
  PluginLoader: Ensure that $site/plugins folder exists
  Plugins#ListRequest: Remove parameter from all() method

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/plugins/PluginApi.java

@@ -0,0 +1,55 @@
+// Copyright (C) 2017 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.api.plugins;
+
+import com.google.gerrit.extensions.common.PluginInfo;
+import com.google.gerrit.extensions.restapi.NotImplementedException;
+import com.google.gerrit.extensions.restapi.RestApiException;
+
+public interface PluginApi {
+  PluginInfo get() throws RestApiException;
+
+  void enable() throws RestApiException;
+
+  void disable() throws RestApiException;
+
+  void reload() throws RestApiException;
+
+  /**
+   * A default implementation which allows source compatibility when adding new methods to the
+   * interface.
+   */
+  class NotImplemented implements PluginApi {
+    @Override
+    public PluginInfo get() throws RestApiException {
+      throw new NotImplementedException();
+    }
+
+    @Override
+    public void enable() throws RestApiException {
+      throw new NotImplementedException();
+    }
+
+    @Override
+    public void disable() throws RestApiException {
+      throw new NotImplementedException();
+    }
+
+    @Override
+    public void reload() throws RestApiException {
+      throw new NotImplementedException();
+    }
+  }
+}

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/plugins/Plugins.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.extensions.api.plugins;
 
+import com.google.gerrit.extensions.common.InstallPluginInput;
 import com.google.gerrit.extensions.common.PluginInfo;
 import com.google.gerrit.extensions.restapi.NotImplementedException;
 import com.google.gerrit.extensions.restapi.RestApiException;
@@ -24,7 +25,11 @@ import java.util.SortedMap;
 
 public interface Plugins {
 
-  ListRequest list();
+  ListRequest list() throws RestApiException;
+
+  PluginApi name(String name) throws RestApiException;
+
+  PluginApi install(String name, InstallPluginInput input) throws RestApiException;
 
   abstract class ListRequest {
     private boolean all;
@@ -40,8 +45,8 @@ public interface Plugins {
 
     public abstract SortedMap<String, PluginInfo> getAsMap() throws RestApiException;
 
-    public ListRequest all(boolean all) {
-      this.all = all;
+    public ListRequest all() {
+      this.all = true;
       return this;
     }
 
@@ -59,5 +64,15 @@ public interface Plugins {
     public ListRequest list() {
       throw new NotImplementedException();
     }
+
+    @Override
+    public PluginApi name(String name) {
+      throw new NotImplementedException();
+    }
+
+    @Override
+    public PluginApi install(String name, InstallPluginInput input) throws RestApiException {
+      throw new NotImplementedException();
+    }
   }
 }