Adding animations for view pager transitions

chrome/android/java/res/layout/tabular_context_menu.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- 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. -->
 <FrameLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:id="@+id/context_menu_frame_layout"
     android:background="@color/modal_dialog_scrim_color" >
 
     <org.chromium.chrome.browser.contextmenu.TabularContextMenuViewPager
         android:id="@+id/custom_pager"
-        android:background="@drawable/white_with_rounded_corners"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginTop="20dp"
         android:layout_marginBottom="20dp"
         android:minWidth="280dp"
         android:layout_gravity="center">
 
         <!-- tabMaxWidth is required otherwise tabGravity will have no effect when the context menu 
              gets too large. -->
         <android.support.design.widget.TabLayout
             android:id="@+id/tab_layout"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:background="@color/google_grey_100"
             app:tabTextColor="@color/black_alpha_54"
             app:tabSelectedTextColor="@color/light_active_color"
             app:tabIndicatorColor="@color/light_active_color"
             app:tabGravity="fill"
             app:tabMode="fixed"
             app:tabMaxWidth="2000dp" />
     </org.chromium.chrome.browser.contextmenu.TabularContextMenuViewPager>
 </FrameLayout>