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

chrome/browser/component_updater/subresource_filter_component_installer.cc

Index: chrome/browser/component_updater/subresource_filter_component_installer.cc
diff --git a/chrome/browser/component_updater/subresource_filter_component_installer.cc b/chrome/browser/component_updater/subresource_filter_component_installer.cc
index a7635db1478e7bb44b010e4b0c83730a1b640e77..7e24099e22c7a36505d80c76aec3565e095c62c8 100644
--- a/chrome/browser/component_updater/subresource_filter_component_installer.cc
+++ b/chrome/browser/component_updater/subresource_filter_component_installer.cc
@@ -112,9 +112,9 @@ std::string SubresourceFilterComponentInstallerTraits::GetName() const {
 
 // 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;