Create the base Custom Context Menu Dialog.

chrome/android/java/src/org/chromium/chrome/browser/contextmenu/CustomContextMenuPagerAdapter.java

Index: chrome/android/java/src/org/chromium/chrome/browser/contextmenu/CustomContextMenuPagerAdapter.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/contextmenu/CustomContextMenuPagerAdapter.java b/chrome/android/java/src/org/chromium/chrome/browser/contextmenu/CustomContextMenuPagerAdapter.java
new file mode 100644
index 0000000000000000000000000000000000000000..8947c86bb40f7ea5e16d7ad01262793111764840
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/contextmenu/CustomContextMenuPagerAdapter.java
@@ -0,0 +1,69 @@
+// 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 CustomContextMenuPagerAdapter extends PagerAdapter {
+    private List<Pair<String, ViewGroup>> mViewList;

[David Trainor- moved to gerrit, 2017/03/21 16:30:02]

I'd say final here as well and everything else that you don't expect/want to
change for the lifecycle of the class (or that you want to guarantee gets set in
constructors).  But I'm ok either way.

[JJ, 2017/03/22 23:35:33]

Done.

+
+    /**
+     * Used in combination of a TabLayout to create a multi view layout.
+     * @param views Thew views to use in the pager Adapter.
+     */
+    CustomContextMenuPagerAdapter(List<Pair<String, ViewGroup>> views) {
+        mViewList = views;
+    }
+
+    // Used thanks due to a bug in displaying RTL.
+    private static int adjustIndexForDirectionality(int index, int count) {

[JJ, 2017/03/17 20:58:20]

Possibly thinking in the future of making a Reversible Pager Adapter to get the
proper position as this is copied off of some other code in the codebase. If so,
do you think this needs a "todo"?

[David Trainor- moved to gerrit, 2017/03/21 16:30:02]

Adding a TODO isn't a bad idea.  Does this logic live in other PagerAdapters in
Chrome?

Also, is this fixed in any version of Android at all?  Or is it still an
existing bug?

[JJ, 2017/03/22 23:35:33]

Likely an existing bug seeing the last edit was in December.
https://cs.chromium.org/chromium/src/chrome/android/java/src/org/chromium/chr...

I'll message the person and see if they have made any progress.

+        if (TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault())

[David Trainor- moved to gerrit, 2017/03/21 16:30:02]

Should we cache whether or not the direction is RTL?

[JJ, 2017/03/22 23:35:32]

Removed static for this class to do this. (I mean I also technically didn't need
to but it didn't really matter).

+                == ViewCompat.LAYOUT_DIRECTION_RTL) {
+            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;
+    }
+}