Remove unused feedback class in dom distiller component

chrome/browser/android/dom_distiller/distiller_ui_handle_android.h

 // Copyright 2015 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 CHROME_BROWSER_ANDROID_DOM_DISTILLER_DISTILLER_UI_HANDLE_ANDROID_H_
 #define CHROME_BROWSER_ANDROID_DOM_DISTILLER_DISTILLER_UI_HANDLE_ANDROID_H_
 
 #include "base/macros.h"
 #include "components/dom_distiller/content/browser/distiller_ui_handle.h"
 #include "content/public/browser/web_contents.h"
 
 namespace dom_distiller {
 
 namespace android {
 
 class DistillerUIHandleAndroid : public DistillerUIHandle {
  public:
   DistillerUIHandleAndroid() {}
   ~DistillerUIHandleAndroid() override {}
 
-  // ExternalFeedbackReporter implementation.
-  void ReportExternalFeedback(content::WebContents* web_contents,
-                              const GURL& url,
-                              const bool good) override;
-
   void OpenSettings(content::WebContents* web_contents) override;
 
   void ClosePanel(bool animate) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DistillerUIHandleAndroid);
 };
 
 }  // namespace android
 
 }  // namespace dom_distiller
 
 #endif  // CHROME_BROWSER_ANDROID_DOM_DISTILLER_DISTILLER_UI_HANDLE_ANDROID_H_