Add method for identifying different InfoBars

chrome/browser/media/midi_permission_infobar_delegate_android.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 CHROME_BROWSER_MEDIA_MIDI_PERMISSION_INFOBAR_DELEGATE_ANDROID_H_
 #define CHROME_BROWSER_MEDIA_MIDI_PERMISSION_INFOBAR_DELEGATE_ANDROID_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 15 matching lines @@
                                    const std::string& display_languages,
                                    const PermissionSetCallback& callback);
 
  private:
   MidiPermissionInfoBarDelegateAndroid(const GURL& requesting_frame,
                                        const std::string& display_languages,
                                        const PermissionSetCallback& callback);
   ~MidiPermissionInfoBarDelegateAndroid() override;
 
   // ConfirmInfoBarDelegate:
+  std::string GetIdentifier() const override;
   int GetIconId() const override;
   base::string16 GetMessageText() const override;
 
   GURL requesting_frame_;
   std::string display_languages_;
 
   DISALLOW_COPY_AND_ASSIGN(MidiPermissionInfoBarDelegateAndroid);
 };
 
 #endif  // CHROME_BROWSER_MEDIA_MIDI_PERMISSION_INFOBAR_DELEGATE_ANDROID_H_