Add global HTTP proxy to Privacy Settings page

This CL allows the user to see on the Enterprise Privacy Settings
page whether the admin set a global HTTP proxy.

Test: make RunSettingsRoboTests
Bug: 32692748

Change-Id: I3c7c46f806f39c90425fd8e098a749f3cc1e9278

src/com/android/settings/enterprise/GlobalHttpProxyPreferenceController.java

@@ -0,0 +1,47 @@
+/*
+ * 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.android.settings.enterprise;
+
+import android.content.Context;
+import android.support.v7.preference.Preference;
+
+import com.android.settings.core.PreferenceController;
+import com.android.settings.overlay.FeatureFactory;
+
+public class GlobalHttpProxyPreferenceController extends PreferenceController {
+
+    private static final String KEY_GLOBAL_HTTP_PROXY = "global_http_proxy";
+    private final EnterprisePrivacyFeatureProvider mFeatureProvider;
+
+    public GlobalHttpProxyPreferenceController(Context context) {
+        super(context);
+        mFeatureProvider = FeatureFactory.getFactory(context)
+                .getEnterprisePrivacyFeatureProvider(context);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        preference.setVisible(mFeatureProvider.isGlobalHttpProxySet());
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return true;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_GLOBAL_HTTP_PROXY;
+    }
+}