Get signals working in the EXTRA_DATA section of MHTML

chrome/browser/flag_descriptions.cc

 // Copyright 2017 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.
 
 #include "chrome/browser/flag_descriptions.h"
 
 namespace flag_descriptions {
 
 //  Material Design version of chrome://bookmarks
 
@@ skipping 2052 matching lines @@
     R"*(that the user can click on it to download the page later.)*";
 
 const char kOfflinePagesSvelteConcurrentLoadingName[] =
     "Enables concurrent background loading on svelte.";
 
 const char kOfflinePagesSvelteConcurrentLoadingDescription[] =
     "Enables concurrent background loading (or downloading) of pages on "
     "Android svelte (512MB RAM) devices. Otherwise, background loading will "
     "happen when the svelte device is idle.";
 
+const char kOfflinePagesLoadSignalCollectingName[] =
+    "Enables collecting load timing data for offline page snapshots.";
+
+const char kOfflinePagesLoadSignalCollectingDescription[] =
+    "Enables loading completeness data collection while writing an offline "
+    "page.  This data is collected in the snapshotted offline page to allow "
+    "data analysis to improve deciding when to make the offline snapshot.";
+
 const char kOfflinePagesPrefetchingName[] =
     "Enables suggested offline pages to be prefetched.";
 
 const char kOfflinePagesPrefetchingDescription[] =
     "Enables suggested offline pages to be prefetched, so useful content is "
     "available while offline.";
 
 const char kOfflinePagesSharingName[] = "Enables offline pages to be shared.";
 
 const char kOfflinePagesSharingDescription[] =
@@ skipping 876 matching lines @@
 const char kEnableCopylessPasteDescription[] =
     "Provide suggestions for text input, based on your recent context. For "
     "example, if you looked at a restaurant website and switched to the Maps "
     "app, the keyboard would offer the name of that restaurant as a suggestion "
     "to enter into the search bar. The data is indexed locally, and never sent "
     "to the server. It's disabled in incognito mode.";
 
 #endif  // defined(OS_ANDROID)
 
 }  // namespace flag_descriptions