Record offline histograms with suffix via Histogram::FactoryGet

components/offline_pages/client_policy_controller.cc

Index: components/offline_pages/client_policy_controller.cc
diff --git a/components/offline_pages/client_policy_controller.cc b/components/offline_pages/client_policy_controller.cc
index 04e8123ca9cac8113a74901e13d7730c576d3685..b8ccb0f679bb9cdf05d057f5f46ed163e28b7c63 100644
--- a/components/offline_pages/client_policy_controller.cc
+++ b/components/offline_pages/client_policy_controller.cc
@@ -7,19 +7,12 @@
 #include <utility>
 
 #include "base/time/time.h"
+#include "components/offline_pages/client_namespace_constants.h"
 
 using LifetimeType = offline_pages::LifetimePolicy::LifetimeType;
 
 namespace offline_pages {
 
-namespace {
-// TODO(romax): These should be moved to a centralized file.
-// Any changes to these well-known namespaces should also be reflected in
-// OfflinePagesNamespace (histograms.xml) for consistency.
-const char kBookmarkNamespace[] = "bookmark";
-const char kLastNNamespace[] = "last_n";
-}  // namespace
-
 ClientPolicyController::ClientPolicyController() {
   policies_.clear();
   // Manually defining client policies for bookmark and last_n.