Turn off "All Bookmarks" completely. Finally.

ios/chrome/browser/experimental_flags.mm

 // 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.
 
 // This file can be empty. Its purpose is to contain the relatively short lived
 // definitions required for experimental flags.
 
 #include "ios/chrome/browser/experimental_flags.h"
 
 #include <dispatch/dispatch.h>
@@ skipping 99 matching lines @@
     return true;
   } else if (command_line->HasSwitch(switches::kDisableAllBookmarksView)) {
     return false;
   }
 
   // Check if the finch experiment exists.
   std::string group_name =
       base::FieldTrialList::FindFullName("RemoveAllBookmarks");
 
   if (group_name.empty()) {
-    return true;  // If no finch experiment, keep all bookmarks enabled.
+    return false;  // If no finch experiment, all bookmarks is disabled.
   }
   return base::StartsWith(group_name, "Enabled",
                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
 bool IsPhysicalWebEnabled() {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kEnableIOSPhysicalWeb)) {
     return true;
   } else if (command_line->HasSwitch(switches::kDisableIOSPhysicalWeb)) {
@@ skipping 63 matching lines @@
   }
 
   // Check if the finch experiment is turned on.
   std::string group_name =
       base::FieldTrialList::FindFullName("SpotlightActionsEnabled");
   return base::StartsWith(group_name, "Enabled",
                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
 }  // namespace experimental_flags