[Offline Pages] Adds new policy bits and reverse lookup.

components/offline_pages/client_policy_controller.h

 // 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.
 
 #ifndef COMPONENTS_OFFLINE_PAGES_CLIENT_POLICY_CONTROLLER_H_
 #define COMPONENTS_OFFLINE_PAGES_CLIENT_POLICY_CONTROLLER_H_
 
 #include <stdint.h>
 
 #include <map>
+#include <memory>
 #include <string>
+#include <vector>
 
 #include "base/time/time.h"
 #include "components/offline_pages/offline_page_client_policy.h"
 
 namespace offline_pages {
 
 // This is the class which is a singleton for offline page model
 // to get client policies based on namespaces.
 class ClientPolicyController {
  public:
   ClientPolicyController();
   ~ClientPolicyController();
 
   // Generates a client policy from the input values.
   static const OfflinePageClientPolicy MakePolicy(
       const std::string& name_space,
       LifetimePolicy::LifetimeType lifetime_type,
       const base::TimeDelta& expiration_period,
       size_t page_limit,
       size_t pages_allowed_per_url);
 
   // Get the client policy for |name_space|.
   const OfflinePageClientPolicy& GetPolicy(const std::string& name_space) const;
 
   // Returns whether pages for |name_space| should be removed on cache reset.
   bool IsRemovedOnCacheReset(const std::string& name_space) const;
 
   // Returns whether pages for |name_space| are shown in Download UI.
   bool IsSupportedByDownload(const std::string& name_space) const;
+  const std::vector<std::string>& GetNamespacesWithDownloadSupport();

[chili, 2016/09/23 23:52:43]

should these methods be const as well?

[dewittj, 2016/09/23 23:55:55]

Because they are memoizing they are not actually const.

[chili, 2016/09/24 00:00:19]

Ah oops forgot about the memoizing bit. darn ^_^

[Dmitry Titov, 2016/09/24 00:09:29]

I think naming-wise, those "get namespaces" methods should follow the "isFoo"
methods, for example in this case, 
GetNamespacesWithDownloadSupport -> GetNamspacesSupportedByDownload

[dewittj, 2016/09/26 23:00:31]

Done.

+
+  // Returns whether pages for |name_space| are shown in recent tabs UI,
+  // currently only available on NTP.
+  bool IsRecentTab(const std::string& name_space) const;

[Dmitry Titov, 2016/09/24 00:09:29]

What is this feature? Can't understand from the comment or the name... Is this
"recently visited sites" on NTP? If so, then maybe call it 
IsShownAsRecentlyVisitedSite ?

[dewittj, 2016/09/26 23:00:31]

Done.

+  const std::vector<std::string>& GetNamespacesForRecentTabs();
+
+  // Returns whether pages for |name_space| should never be shown outside the
+  // tab they were generated in.
+  bool ShouldOnlyBeShownInOriginalTab(const std::string& name_space) const;

[Dmitry Titov, 2016/09/24 00:09:29]

Naming suggestion: IsRestrictedToOriginalTab

[dewittj, 2016/09/26 23:00:31]

Done.

+  const std::vector<std::string>& GetNamespacesToShowInOriginalTab();
 
  private:
   // The map from name_space to a client policy. Will be generated
   // as pre-defined values for now.
   std::map<std::string, OfflinePageClientPolicy> policies_;
 
+  // Memoizing results.
+  std::unique_ptr<std::vector<std::string>> download_namespace_cache_;
+  std::unique_ptr<std::vector<std::string>> recent_tab_namespace_cache_;
+  std::unique_ptr<std::vector<std::string>> show_in_original_tab_cache_;
+
   DISALLOW_COPY_AND_ASSIGN(ClientPolicyController);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_CLIENT_POLICY_CONTROLLER_H_