Make call sites of subresource_filter::GetActiveConfigurations const-correct.

chrome/browser/component_updater/subresource_filter_component_installer.cc

 // 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.
 
 #include "chrome/browser/component_updater/subresource_filter_component_installer.h"
 
 #include <utility>
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
@@ skipping 94 matching lines @@
     std::vector<uint8_t>* hash) const {
   hash->assign(std::begin(kPublicKeySHA256), std::end(kPublicKeySHA256));
 }
 
 std::string SubresourceFilterComponentInstallerTraits::GetName() const {
   return kSubresourceFilterSetFetcherManifestName;
 }
 
 // static
 std::string SubresourceFilterComponentInstallerTraits::GetInstallerTag() {
-  std::string ruleset_flavor = subresource_filter::GetActiveConfigurations()
-                                   ->the_one_and_only()
-                                   .ruleset_flavor;
+  const auto configurations = subresource_filter::GetActiveConfigurations();
+  const std::string ruleset_flavor =

[pkalinnikov, 2017/04/26 09:20:19]

nit: Why not const ref? Seems all the way the same (but copy instead of
copy+move), except when the flow goes down to return "invalid". Unless I am
missing some RVO subtleties.

[engedy, 2017/04/26 10:00:31]

No reason, I just didn't realize that a reference can be taken here. Done.

+      configurations->the_one_and_only().ruleset_flavor;
   if (ruleset_flavor.empty())
     return ruleset_flavor;
 
   // We allow 4 ruleset flavor identifiers: a, b, c, d
   if (ruleset_flavor.size() == 1 && ruleset_flavor.at(0) >= 'a' &&
       ruleset_flavor.at(0) <= 'd')

[pkalinnikov, 2017/04/26 09:20:19]

I vaguely remember that we had a rule to put a statement into braces if the
condition spans multiple lines. Unfortunately, I couldn't find it in the
guidelines. Am I missing something?

[engedy, 2017/04/26 10:00:31]

I, too, am unable to find it, and I could not find any announcements about a
change here. Added curlies for good measure.

     return ruleset_flavor;
 
   // Return 'invalid' for any cases where we encounter an invalid installer
   // tag. This allows us to verify that no clients are encountering invalid
   // installer tags in the field.
   return "invalid";
 }
 
 update_client::InstallerAttributes
 SubresourceFilterComponentInstallerTraits::GetInstallerAttributes() const {
   update_client::InstallerAttributes attributes;
   std::string installer_tag = GetInstallerTag();
   if (!installer_tag.empty())
     attributes["tag"] = installer_tag;
   return attributes;
 }
 
 std::vector<std::string>
 SubresourceFilterComponentInstallerTraits::GetMimeTypes() const {
   return std::vector<std::string>();
 }
 
 void RegisterSubresourceFilterComponent(ComponentUpdateService* cus) {
   if (!base::FeatureList::IsEnabled(
           subresource_filter::kSafeBrowsingSubresourceFilter))

[pkalinnikov, 2017/04/26 09:20:18]

Same as above.

[engedy, 2017/04/26 10:00:31]

Done.

     return;
   std::unique_ptr<ComponentInstallerTraits> traits(
       new SubresourceFilterComponentInstallerTraits());
   // |cus| will take ownership of |installer| during installer->Register(cus).
   DefaultComponentInstaller* installer =
       new DefaultComponentInstaller(std::move(traits));
   installer->Register(cus, base::Closure());
 }
 
 }  // namespace component_updater