Remove unused feedback class in dom distiller component

components/dom_distiller/content/browser/distiller_ui_handle.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 COMPONENTS_DOM_DISTILLER_CONTENT_BROWSER_DISTILLER_UI_HANDLE_H_
 #define COMPONENTS_DOM_DISTILLER_CONTENT_BROWSER_DISTILLER_UI_HANDLE_H_
 
 #include "base/macros.h"
 #include "content/public/browser/web_contents.h"
 #include "url/gurl.h"
 
 namespace dom_distiller {
 
 // ExternalFeedbackReporter handles reporting distillation quality through an
 // external source.
 class DistillerUIHandle {
  public:
   DistillerUIHandle() {}
   virtual ~DistillerUIHandle() {}
 
-  // Start an external form to record user feedback.
-  virtual void ReportExternalFeedback(content::WebContents* web_contents,
-                                      const GURL& url,
-                                      const bool good) = 0;
-
   // Open the UI settings for dom distiller.
   virtual void OpenSettings(content::WebContents* web_contents) = 0;
 
   // Close the Reader Mode panel.
   virtual void ClosePanel(bool animate) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DistillerUIHandle);
 };
 
 }  // namespace dom_distiller
 
 #endif  // COMPONENTS_DOM_DISTILLER_CONTENT_BROWSER_DISTILLER_UI_HANDLE_H_