[Offline Pages] Set up the initial prefetching service.

components/offline_pages/core/client_policy_controller.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 "components/offline_pages/core/client_policy_controller.h"
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 #include "base/time/time.h"
@@ skipping 36 matching lines @@
                               .SetIsRemovedOnCacheReset(false)
                               .SetIsSupportedByDownload(true)
                               .Build()));
   policies_.insert(std::make_pair(
       kNTPSuggestionsNamespace,
       OfflinePageClientPolicyBuilder(kNTPSuggestionsNamespace,
                                      LifetimeType::PERSISTENT, kUnlimitedPages,
                                      kUnlimitedPages)
           .SetIsSupportedByDownload(true)
           .Build()));
+  policies_.insert(std::make_pair(
+      kSuggestedArticlesNamespace,
+      OfflinePageClientPolicyBuilder(kSuggestedArticlesNamespace,
+                                     LifetimeType::TEMPORARY, kUnlimitedPages,
+                                     kUnlimitedPages)
+          .SetIsRemovedOnCacheReset(true)
+          .SetExpirePeriod(base::TimeDelta::FromDays(30))
+          .Build()));
 
   // Fallback policy.
   policies_.insert(std::make_pair(
       kDefaultNamespace, MakePolicy(kDefaultNamespace, LifetimeType::TEMPORARY,
                                     base::TimeDelta::FromDays(1), 10, 1)));
 }
 
 ClientPolicyController::~ClientPolicyController() {}
 
 // static
@@ skipping 87 matching lines @@
   return *show_in_original_tab_cache_;
 }
 
 void ClientPolicyController::AddPolicyForTest(
     const std::string& name_space,
     const OfflinePageClientPolicyBuilder& builder) {
   policies_.insert(std::make_pair(name_space, builder.Build()));
 }
 
 }  // namespace offline_pages