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

chrome/android/java/src/org/chromium/chrome/browser/preferences/SearchEnginePreference.java

 // 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.
 
 package org.chromium.chrome.browser.preferences;
 
 import android.os.Bundle;
 import android.preference.PreferenceFragment;
 import android.view.LayoutInflater;
 import android.view.View;
-import android.view.View.OnLayoutChangeListener;
 import android.view.ViewGroup;
 import android.widget.ListView;
 
 import org.chromium.base.VisibleForTesting;
-import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.chrome.R;
-import org.chromium.chrome.browser.locale.LocaleManager;
-import org.chromium.chrome.browser.search_engines.TemplateUrlService;
 
 /**
 * A preference fragment for selecting a default search engine.
 */
-public class SearchEnginePreference extends PreferenceFragment
-        implements View.OnClickListener, SearchEngineAdapter.SelectSearchEngineCallback,
-                   OnLayoutChangeListener {
+public class SearchEnginePreference extends PreferenceFragment {
     private ListView mListView;
-    private View mCancelButton;
-    private View mSaveButton;
-    private View mDivider;
 
     private SearchEngineAdapter mSearchEngineAdapter;
-    private int mSelectedIndex;
 
     @VisibleForTesting
     String getValueForTesting() {
         return mSearchEngineAdapter.getValueForTesting();
     }
 
     @VisibleForTesting
-    void setValueForTesting(String value) {
-        mSearchEngineAdapter.setValueForTesting(value);
-        TemplateUrlService.getInstance().setSearchEngine(mSelectedIndex);
+    String setValueForTesting(String value) {
+        return mSearchEngineAdapter.setValueForTesting(value);
+    }
+
+    @VisibleForTesting
+    String getKeywordFromIndexTesting(int index) {
+        return mSearchEngineAdapter.getKeywordForTesting(index);
     }
 
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         getActivity().setTitle(R.string.prefs_search_engine);
-        mSearchEngineAdapter = new SearchEngineAdapter(getActivity(), this);
+        mSearchEngineAdapter = new SearchEngineAdapter(getActivity());
     }
 
     @Override
     public View onCreateView(
             LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         View view = inflater.inflate(R.layout.search_engine_layout, container, false);
         mListView = (ListView) view.findViewById(android.R.id.list);
         mListView.setAdapter(mSearchEngineAdapter);
         mListView.setDivider(null);
-        mListView.addOnLayoutChangeListener(this);
-        mCancelButton = view.findViewById(R.id.cancel_button);
-        mCancelButton.setOnClickListener(this);
-        mSaveButton = view.findViewById(R.id.save_button);
-        mSaveButton.setOnClickListener(this);
-        mDivider = view.findViewById(R.id.bottom_shadow);
         return view;
     }
 
     @Override
-    public void onActivityCreated(Bundle savedInstanceState) {
-        super.onActivityCreated(savedInstanceState);
-    }
-
-    @Override
-    public void onClick(View v) {
-        if (v == mCancelButton) {
-            getActivity().finish();
-        } else if (v == mSaveButton) {
-            TemplateUrlService.getInstance().setSearchEngine(mSelectedIndex);
-            // If the user has manually set the default search engine, disable auto switching.
-            boolean manualSwitch = mSelectedIndex == mSearchEngineAdapter
-                    .getInitialSearchEnginePosition();
-            if (manualSwitch) {
-                RecordUserAction.record("SearchEngine_ManualChange");
-                LocaleManager.getInstance().setSearchEngineAutoSwitch(false);
-            }
-            getActivity().finish();
-        }
-    }
-
-    @Override
-    public void currentSearchEngineDetermined(int selectedIndex) {
-        mSelectedIndex = selectedIndex;
-    }
-
-    /**
-     * Displays the divider if the Listview is longer than its viewport.
-     */
-    public void updateBottombarDivider() {
-        if (mListView.getLastVisiblePosition() == mSearchEngineAdapter.getCount() - 1) {
-            mDivider.setVisibility(View.INVISIBLE);
-        } else {
-            mDivider.setVisibility(View.VISIBLE);
-        }
-    }
-
-    @Override
-    public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft,
-            int oldTop, int oldRight, int oldBottom) {
-        if (v == mListView) {
-            updateBottombarDivider();
-        }
-    }
-
-    @Override
     public void onResume() {
         super.onResume();
         /**
          * Handle UI update when location setting for a search engine is changed.
          */
         mSearchEngineAdapter.notifyDataSetChanged();
     }
 }