Create the base Custom Context Menu Dialog.

chrome/android/java/src/org/chromium/chrome/browser/contextmenu/TabularContextMenuPagerAdapter.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.chrome.browser.contextmenu;
+
+import android.support.v4.text.TextUtilsCompat;
+import android.support.v4.view.PagerAdapter;
+import android.support.v4.view.ViewCompat;
+import android.util.Pair;
+import android.view.View;
+import android.view.ViewGroup;
+
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * Takes a list of views and strings and creates a wrapper for the ViewPager and Tab adapter.
+ */
+class TabularContextMenuPagerAdapter extends PagerAdapter {
+    private final List<Pair<String, ViewGroup>> mViewList;
+    private final boolean mIsRightToLeft;
+
+    /**
+     * Used in combination of a TabLayout to create a multi view layout.
+     * @param views Thew views to use in the pager Adapter.
+     */
+    TabularContextMenuPagerAdapter(List<Pair<String, ViewGroup>> views) {
+        mViewList = views;
+        mIsRightToLeft = TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault())
+                == ViewCompat.LAYOUT_DIRECTION_RTL;
+    }
+
+    // Addresses the RTL display bug: https://code.google.com/p/android/issues/detail?id=56831
+    private int adjustIndexForDirectionality(int index, int count) {
+        if (mIsRightToLeft) {
+            return count - 1 - index;
+        }
+        return index;
+    }
+
+    @Override
+    public Object instantiateItem(ViewGroup container, int position) {
+        position = adjustIndexForDirectionality(position, getCount());
+        ViewGroup layout = mViewList.get(position).second;
+        container.addView(layout);
+        return layout;
+    }
+
+    @Override
+    public void destroyItem(ViewGroup container, int position, Object object) {
+        position = adjustIndexForDirectionality(position, getCount());
+        container.removeViewAt(position);
+    }
+
+    @Override
+    public int getCount() {
+        return mViewList.size();
+    }
+
+    @Override
+    public boolean isViewFromObject(View view, Object object) {
+        return view == object;
+    }
+
+    @Override
+    public CharSequence getPageTitle(int position) {
+        position = adjustIndexForDirectionality(position, getCount());
+        return mViewList.get(position).first;
+    }
+}