Remove the unused parts of PPB_PDF

chrome/browser/ui/pdf/chrome_pdf_web_contents_helper_client.h

 // Copyright 2014 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_UI_PDF_CHROME_PDF_WEB_CONTENTS_HELPER_CLIENT_H_
 #define CHROME_BROWSER_UI_PDF_CHROME_PDF_WEB_CONTENTS_HELPER_CLIENT_H_
 
 #include "base/macros.h"
 #include "components/pdf/browser/pdf_web_contents_helper_client.h"
 
 class ChromePDFWebContentsHelperClient
     : public pdf::PDFWebContentsHelperClient {
  public:
   ChromePDFWebContentsHelperClient();
   ~ChromePDFWebContentsHelperClient() override;
 
  private:
   // pdf::PDFWebContentsHelperClient:
   void UpdateLocationBar(content::WebContents* contents) override;
 
   void UpdateContentRestrictions(content::WebContents* contents,
                                  int content_restrictions) override;
 
   void OnPDFHasUnsupportedFeature(content::WebContents* contents) override;
 
   void OnSaveURL(content::WebContents* contents) override;
 
-  void OnShowPDFPasswordDialog(
-      content::WebContents* contents,
-      const base::string16& prompt,
-      const pdf::PasswordDialogClosedCallback& callback) override;
-
   DISALLOW_COPY_AND_ASSIGN(ChromePDFWebContentsHelperClient);
 };
 
-void ShowPDFPasswordDialog(content::WebContents* web_contents,
-                           const base::string16& prompt,
-                           const pdf::PasswordDialogClosedCallback& callback);
-
 #endif  // CHROME_BROWSER_UI_PDF_CHROME_PDF_WEB_CONTENTS_HELPER_CLIENT_H_