[WebView] Remove more redundant classes

android_webview/browser/aw_web_preferences_populater.h

 // Copyright 2013 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.
 
 #ifndef ANDROID_WEBVIEW_BROWSER_AW_WEB_PREFERENCES_POPULATER_H_
 #define ANDROID_WEBVIEW_BROWSER_AW_WEB_PREFERENCES_POPULATER_H_
 
 namespace content {
 class WebContents;
 struct WebPreferences;
 }
 
 namespace android_webview {
 
 // Empty base class so this can be destroyed by AwContentBrowserClient.
 class AwWebPreferencesPopulater {
  public:
-  virtual ~AwWebPreferencesPopulater();
+  AwWebPreferencesPopulater() = default;
+  ~AwWebPreferencesPopulater() = default;
 
-  virtual void PopulateFor(content::WebContents* web_contents,
-                           content::WebPreferences* web_prefs) = 0;
+  void PopulateFor(content::WebContents* web_contents,
+                   content::WebPreferences* web_prefs);
 };
 
 }  // namespace android_webview
 
 #endif  // ANDROID_WEBVIEW_BROWSER_AW_WEB_PREFERENCES_POPULATER_H_