Track Previews infobar dismissals due to tab closure

chrome/browser/previews/previews_infobar_delegate.h

 // Copyright 2016 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_PREVIEWS_PREVIEWS_INFOBAR_DELEGATE_H_
 #define CHROME_BROWSER_PREVIEWS_PREVIEWS_INFOBAR_DELEGATE_H_
 
 #include "base/callback.h"
 #include "base/strings/string16.h"
 #include "components/infobars/core/confirm_infobar_delegate.h"
@@ skipping 19 matching lines @@
   typedef base::Callback<void(bool opt_out)> OnDismissPreviewsInfobarCallback;
 
   // Actions on the previews infobar. This enum must remain synchronized with
   // the enum of the same name in metrics/histograms/histograms.xml.
   enum PreviewsInfoBarAction {
     INFOBAR_SHOWN = 0,
     INFOBAR_LOAD_ORIGINAL_CLICKED = 1,
     INFOBAR_DISMISSED_BY_USER = 2,
     INFOBAR_DISMISSED_BY_NAVIGATION = 3,
     INFOBAR_DISMISSED_BY_RELOAD = 4,
+    INFOBAR_DISMISSED_BY_TAB_CLOSURE = 5,
     INFOBAR_INDEX_BOUNDARY
   };
 
   ~PreviewsInfoBarDelegate() override;
 
   // Creates a preview infobar and corresponding delegate and adds the infobar
   // to InfoBarService.
   static void Create(
       content::WebContents* web_contents,
       PreviewsInfoBarType infobar_type,
@@ skipping 11 matching lines @@
   infobars::InfoBarDelegate::InfoBarIdentifier GetIdentifier() const override;
   int GetIconId() const override;
   bool ShouldExpire(const NavigationDetails& details) const override;
   void InfoBarDismissed() override;
   base::string16 GetMessageText() const override;
   int GetButtons() const override;
   base::string16 GetLinkText() const override;
   bool LinkClicked(WindowOpenDisposition disposition) override;
 
   PreviewsInfoBarType infobar_type_;
+  mutable PreviewsInfoBarAction infobar_dismissed_action_;
 
   const base::string16 message_text_;
 
   OnDismissPreviewsInfobarCallback on_dismiss_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(PreviewsInfoBarDelegate);
 };
 
 #endif  // CHROME_BROWSER_PREVIEWS_PREVIEWS_INFOBAR_DELEGATE_H_