Get signals working in the EXTRA_DATA section of MHTML

chrome/browser/android/offline_pages/offline_page_mhtml_archiver.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 CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_MHTML_ARCHIVER_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_MHTML_ARCHIVER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 31 matching lines @@
 //   }
 class OfflinePageMHTMLArchiver : public OfflinePageArchiver {
  public:
 
   explicit OfflinePageMHTMLArchiver(content::WebContents* web_contents);
   ~OfflinePageMHTMLArchiver() override;
 
   // OfflinePageArchiver implementation:
   void CreateArchive(const base::FilePath& archives_dir,
                      const CreateArchiveParams& create_archive_params,
+                     const std::string& signal_data,
                      const CreateArchiveCallback& callback) override;
 
  protected:
   // Allows to overload the archiver for testing.
   OfflinePageMHTMLArchiver();
 
   // Try to generate MHTML.
   // Might be overridden for testing purpose.
   virtual void GenerateMHTML(const base::FilePath& archives_dir,
                              const CreateArchiveParams& create_archive_params);
 
   // Callback for Generating MHTML.
   void OnGenerateMHTMLDone(const GURL& url,
                            const base::FilePath& file_path,
                            const base::string16& title,
                            int64_t file_size);
 
   // Checks whether the page to be saved has security error when loaded over
   // HTTPS. Saving a page will fail if that is the case. HTTP connections are
   // not affected.
   virtual bool HasConnectionSecurityError();
 
   // Reports failure to create archive a page to the client that requested it.
   void ReportFailure(ArchiverResult result);
 
  private:
   // Contents of the web page to be serialized. Not owned.
   content::WebContents* web_contents_;
 
+  // Saved signal data corresponding to this page load. This is a way of logging
+  // signals that have been received as of the time of the page capture to help
+  // training a recognizer for when to take a snapshot.
+  std::string signal_data_;
+
   CreateArchiveCallback callback_;
 
   base::WeakPtrFactory<OfflinePageMHTMLArchiver> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageMHTMLArchiver);
 };
 
 }  // namespace offline_pages
 
 #endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_MHTML_ARCHIVER_H_