Content class factory and generalized text selector

content/public/android/java/src/org/chromium/content/browser/ContentClassFactory.java

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.content.browser;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.ui.base.WindowAndroid;
+
+/**
+ * A class factory for content browser layer.
+ */
+public class ContentClassFactory {
+    private static ContentClassFactory sSingleton;
+
+    /**
+     * Sets the factory object.
+     */
+    public static void set(ContentClassFactory factory) {
+        ThreadUtils.assertOnUiThread();
+
+        sSingleton = factory;
+    }
+
+    /**
+     * Returns the factory object.
+     */
+    public static ContentClassFactory get() {
+        ThreadUtils.assertOnUiThread();
+
+        if (sSingleton == null) sSingleton = new ContentClassFactory();
+        return sSingleton;
+    }
+
+    /**
+     * Constructor.
+     */
+    protected ContentClassFactory() {}
+
+    /**
+     * Creates ContextSelectorProvider object.
+     */
+    public ContextSelectionProvider createContextSelectionProvider(
+            ContextSelectionProvider.ResultCallback callback, WindowAndroid windowAndroid) {
+        // Implemented by a subclass.
+        return null;
+    }
+}