[Offline Pages] Fix several infobar bugs.

chrome/browser/android/offline_pages/downloads/offline_page_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_ANDROID_OFFLINE_PAGES_DOWNLOADS_OFFLINE_PAGE_INFOBAR_DELEGATE_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_DOWNLOADS_OFFLINE_PAGE_INFOBAR_DELEGATE_H_
 
 #include "base/callback_forward.h"
 #include "chrome/browser/android/download/download_overwrite_infobar_delegate.h"
 #include "components/infobars/core/infobar_delegate.h"
 
 namespace content {
 class WebContents;
 }
 
 namespace offline_pages {
 
+// An InfoBarDelegate that appears when a user attempt to save offline pages for
+// a URL that is already saved.  This piggy-backs off the Download infobar,
+// since the UI should be the same between Downloads and Offline Pages in this
+// case.  There are two actions: Create New, and Overwrite.  Since Overwrite is
+// not straightforward for offline pages, the behavior is to delete ALL other
+// pages that are saved for the given URL, then save the newly requested page.
 class OfflinePageInfoBarDelegate
     : public chrome::android::DownloadOverwriteInfoBarDelegate {
  public:
+  enum class Action { CREATE_NEW, OVERWRITE };
+
   // Creates an offline page infobar and a delegate and adds the infobar to the
   // InfoBarService associated with |web_contents|. |page_name| is the name
   // shown for this file in the infobar text.
-  static void Create(const base::Closure& confirm_continuation,
+  static void Create(const base::Callback<void(Action)>& confirm_continuation,
+                     const std::string& downloads_label,
                      const std::string& page_name,
                      content::WebContents* web_contents);
   ~OfflinePageInfoBarDelegate() override;
 
  private:
-  OfflinePageInfoBarDelegate(const base::Closure& confirm_continuation,
-                             const std::string& page_name);
+  OfflinePageInfoBarDelegate(
+      const base::Callback<void(Action)>& confirm_continuation,
+      const std::string& downloads_label,
+      const std::string& page_name);
 
   // DownloadOverwriteInfoBarDelegate:
   infobars::InfoBarDelegate::InfoBarIdentifier GetIdentifier() const override;
   bool EqualsDelegate(InfoBarDelegate* delegate) const override;
   bool OverwriteExistingFile() override;
   bool CreateNewFile() override;
   std::string GetFileName() const override;
   std::string GetDirName() const override;
   std::string GetDirFullPath() const override;
   bool ShouldExpire(const NavigationDetails& details) const override;
   OfflinePageInfoBarDelegate* AsOfflinePageInfoBarDelegate() override;
 
   // Continuation called when the user chooses to create a new file.
-  base::Closure confirm_continuation_;
+  base::Callback<void(Action)> confirm_continuation_;
 
+  std::string downloads_label_;
   std::string page_name_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageInfoBarDelegate);
 };
 
 }  // namespace offline_pages
 
 #endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_DOWNLOADS_OFFLINE_PAGE_INFOBAR_DELEGATE_H_