[Android] Allow setting recently visited search engines as default search engine

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

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2016 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. -->
 
 <LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:chrome="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:paddingTop="6dp"
     android:orientation="vertical">
     
     <ListView
         android:id="@android:id/list"
         android:layout_width="match_parent"
-        android:layout_height="0dp"
-        android:layout_weight="1"/>
-    
-    <View
-        android:id="@+id/bottom_shadow"
-        android:layout_width="match_parent"
-        android:layout_height="1dp"
-        android:background="@drawable/toolbar_shadow_normal"
-        android:scaleY="-1" 
-        android:visibility="invisible" />
-        
-    <LinearLayout
-        android:layout_width="match_parent"
-        android:layout_height="56dp"
-        android:orientation="horizontal"
-        android:gravity="end"
-        android:paddingStart="6dp"
-        android:paddingEnd="6dp">
-      
-         <Button
-             android:id="@+id/cancel_button"
-             style="@style/ButtonCompatBorderless"
-             android:layout_width="wrap_content"
-             android:layout_height="wrap_content"
-             android:textColor="@color/light_active_color"
-             android:text="@string/cancel"
-             android:textAllCaps="true"
-             android:textSize="14sp"
-             android:layout_marginEnd="16dp"
-             android:layout_gravity="center_vertical"/>
-          
-         <org.chromium.ui.widget.ButtonCompat
-             android:id="@+id/save_button"
-             android:layout_width="wrap_content"
-             android:layout_height="wrap_content"
-             android:textColor="@android:color/white"
-             android:text="@string/save"
-             android:textAllCaps="true"
-             android:textSize="14sp"
-             android:layout_marginEnd="8dp"
-             chrome:buttonColor="@color/light_active_color"
-             chrome:buttonRaised="false"
-             android:layout_gravity="center_vertical"/>
-          
-    </LinearLayout>
+        android:layout_height="match_parent"/>

[Ian Wen, 2016/10/26 18:56:14]

Since this layout is so simple now, it makes me think if it is necessary.

If you call super in SearchEnginePreference#onCreateView() to inflate the
default layout, and then find the list using the same id, I think it should just
work.

Another example is that SiteSettingsPreferences is a list and it does not need
to override onCreateView().

[ltian, 2016/10/28 22:00:26]

Done.

     
 </LinearLayout>