SuggestionsService undo blacklist functionality.

components/suggestions/blacklist_store.h

 // Copyright 2014 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_SUGGESTIONS_BLACKLIST_STORE_H_
 #define COMPONENTS_SUGGESTIONS_BLACKLIST_STORE_H_
 
+#include <map>
+#include <string>
+
 #include "base/macros.h"
+#include "base/time/time.h"
 #include "components/suggestions/proto/suggestions.pb.h"
 #include "url/gurl.h"
 
 class PrefService;
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }  // namespace user_prefs
 
 namespace suggestions {
 
-// A helper class for reading, writing and modifying a small blacklist stored
-// in the Profile preferences. It also handles SuggestionsProfile
-// filtering based on the stored blacklist.
+// A helper class for reading, writing, modifying and applying a small URL
+// blacklist, pending upload to the server. The class has a concept of time
+// duration before which a blacklisted URL becomes candidate for upload to the
+// server. Keep in mind most of the operations involve interaction with the disk
+// (the profile's preferences). Note that the class should be used as a
+// singleton for the upload candidacy to work properly.
 class BlacklistStore {
  public:
-  explicit BlacklistStore(PrefService* profile_prefs);
+  BlacklistStore(
+      PrefService* profile_prefs,
+      const base::TimeDelta& upload_delay = base::TimeDelta::FromSeconds(15));
   virtual ~BlacklistStore();
 
-  // Returns true if successful or |url| was already in the blacklist.
+  // Returns true if successful or |url| was already in the blacklist. If |url|
+  // was already in the blacklist, its blacklisting timestamp gets updated.
   virtual bool BlacklistUrl(const GURL& url);
 
-  // Sets |url| to the first URL from the blacklist. Returns false if the
+  // Gets the time until any URL is ready for upload. Returns false if the
   // blacklist is empty.
-  virtual bool GetFirstUrlFromBlacklist(GURL* url);
+  virtual bool GetTimeUntilReadyForUpload(base::TimeDelta* delta);
 
-  // Removes |url| from the stored blacklist. Returns true if successful or if
-  // |url| is not in the blacklist.
+  // Gets the time until |url| is ready for upload. Returns false if |url| is
+  // not part of the blacklist.
+  virtual bool GetTimeUntilURLReadyForUpload(const GURL& url,
+                                             base::TimeDelta* delta);
+
+  // Sets |url| to a URL from the blacklist that is candidate for upload.
+  // Returns false if there is no candidate for upload.
+  virtual bool GetCandidateForUpload(GURL* url);
+
+  // Removes |url| from the stored blacklist. Returns true if successful, false
+  // on failure or if |url| was not in the blacklist. Note that this function
+  // does not enforce a minimum time since blacklist before removal.
   virtual bool RemoveUrl(const GURL& url);
 
   // Applies the blacklist to |suggestions|.
   virtual void FilterSuggestions(SuggestionsProfile* suggestions);
 
   // Register BlacklistStore related prefs in the Profile prefs.
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
  protected:
   // Test seam. For simplicity of mock creation.
   BlacklistStore() {}
 
   // Loads the blacklist data from the Profile preferences into
   // |blacklist|. If there is a problem with loading, the pref value is
   // cleared, false is returned and |blacklist| is cleared. If successful,
   // |blacklist| will contain the loaded data and true is returned.
   bool LoadBlacklist(SuggestionsBlacklist* blacklist);
 
   // Stores the provided |blacklist| to the Profile preferences, using
   // a base64 encoding of its protobuf serialization.
   bool StoreBlacklist(const SuggestionsBlacklist& blacklist);
 
   // Clears any blacklist data from the profile's preferences.
   void ClearBlacklist();
 
  private:
   // The pref service used to persist the suggestions blacklist.
   PrefService* pref_service_;
 
+  // Delay after which a URL becomes candidate for upload, measured from the
+  // last time the URL was added.
+  base::TimeDelta upload_delay_;
+
+  // The times at which URLs were blacklisted. Used to determine when a URL is
+  // valid for server upload. Guaranteed to contain URLs that are not ready for
+  // upload. Might not contain URLs that are ready for upload.
+  std::map<std::string, base::TimeTicks> blacklist_times_;
+
   DISALLOW_COPY_AND_ASSIGN(BlacklistStore);
 };
 
 }  // namespace suggestions
 
 #endif  // COMPONENTS_SUGGESTIONS_BLACKLIST_STORE_H_