Make USB permissions work in the new permission message system

chrome/common/extensions/permissions/chrome_permission_message_provider.cc

 // Copyright 2013 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/common/extensions/permissions/chrome_permission_message_provider.h"
 
 #include <vector>
 
 #include "base/memory/scoped_vector.h"
 #include "base/metrics/field_trial.h"
@@ skipping 49 matching lines @@
     const PermissionIDSet& permissions) const {
   std::vector<ChromePermissionMessageRule> rules =
       ChromePermissionMessageRule::GetAllRules();
 
   // Apply each of the rules, in order, to generate the messages for the given
   // permissions. Once a permission is used in a rule, remove it from the set
   // of available permissions so it cannot be applied to subsequent rules.
   PermissionIDSet remaining_permissions = permissions;
   CoalescedPermissionMessages messages;
   for (const auto& rule : rules) {
-    // Only apply the rule if we have all the required permission IDs.
-    if (remaining_permissions.ContainsAllIDs(rule.required_permissions())) {
+    // Only apply the rule if we have all the required permission IDs. If the
+    // rule has no required IDs, then apply it only if any of the optional ones
+    // are there.
+    bool has_required_permissions = !rule.required_permissions().empty();
+    bool use_rule =
+        has_required_permissions
+            ? remaining_permissions.ContainsAllIDs(rule.required_permissions())
+            : remaining_permissions.ContainsAnyID(rule.optional_permissions());
+    if (use_rule) {
       // We can apply the rule. Add all the required permissions, and as many
       // optional permissions as we can, to the new message.
       PermissionIDSet used_permissions =
           remaining_permissions.GetAllPermissionsWithIDs(
               rule.all_permissions());
       messages.push_back(rule.GetPermissionMessage(used_permissions));
 
       remaining_permissions =
           PermissionIDSet::Difference(remaining_permissions, used_permissions);
     }
@@ skipping 166 matching lines @@
   std::set<std::string> old_hosts_set(
       permission_message_util::GetDistinctHosts(old_list, false, false));
   std::set<std::string> new_hosts_only =
       base::STLSetDifference<std::set<std::string> >(new_hosts_set,
                                                      old_hosts_set);
 
   return !new_hosts_only.empty();
 }
 
 }  // namespace extensions