Add filtering logic for client-side variations.

chrome/browser/metrics/variations_service.h

 // Copyright (c) 2012 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 CHROME_BROWSER_METRICS_VARIATIONS_SERVICE_H_
 #define CHROME_BROWSER_METRICS_VARIATIONS_SERVICE_H_
 #pragma once
 
+#include <string>
+
 #include "base/compiler_specific.h"
+#include "base/gtest_prod_util.h"
+#include "base/time.h"
 #include "base/memory/scoped_ptr.h"
+#include "chrome/browser/metrics/proto/study.pb.h"
 #include "chrome/browser/metrics/proto/trials_seed.pb.h"
+#include "chrome/common/chrome_version_info.h"
 #include "content/public/common/url_fetcher_delegate.h"
 
 template <typename T> struct DefaultSingletonTraits;
 class PrefService;
 
 // Used to setup field trials based on stored variations seed data, and fetch
 // new seed data from the variations server.
 class VariationsService : public content::URLFetcherDelegate {
  public:
   // Returns the singleton instance;
   static VariationsService* GetInstance();
 
   // Loads the Variations seed data from the given local prefs. If there is a
   // problem with loading, the pref value is cleared.
   void LoadVariationsSeed(PrefService* local_prefs);
 
   // Starts the fetching process, where |OnURLFetchComplete| is called with the
   // response.
   void StartFetchingVariationsSeed();
 
   // content::URLFetcherDelegate implementation:
   virtual void OnURLFetchComplete(const content::URLFetcher* source) OVERRIDE;
 
   // Register Variations related prefs in Local State.
   static void RegisterPrefs(PrefService* prefs);
 
  private:
   friend struct DefaultSingletonTraits<VariationsService>;
 
+  FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyChannel);
+  FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyVersion);
+  FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyVersionWildcards);
+  FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyDate);
+
   VariationsService();
   virtual ~VariationsService();
 
   // Store the given seed data to the given local prefs. Note that |seed_data|
   // is assumed to be the raw serialized protobuf data stored in a string. It
   // will be Base64Encoded for storage. If the string is invalid or the encoding
   // fails, the |local_prefs| is left as is.
   void StoreSeedData(const std::string& seed_data, PrefService* local_prefs);
 
+  // Returns whether |study| should be added to the local field trials list
+  // according to its restriction parameters.
+  static bool ShouldAddStudy(const chrome_variations::Study& study);
+
+  // Checks whether |study| is applicable for the given |channel|.
+  static bool CheckStudyChannel(const chrome_variations::Study& study,
+                                chrome::VersionInfo::Channel channel);
+
+  // Checks whether |study| is applicable for the given version string.
+  static bool CheckStudyVersion(const chrome_variations::Study& study,
+                                const std::string& version_string);
+
+  // Checks whether |study| is applicable for the given date/time.
+  static bool CheckStudyDate(const chrome_variations::Study& study,
+                             const base::Time& date_time);
+
   // Contains the current seed request. Will only have a value while a request
   // is pending, and will be reset by |OnURLFetchComplete|.
   scoped_ptr<content::URLFetcher> pending_seed_request_;
 
   // The variations seed data being used for this session.
   // TODO(jwd): This should be removed. When the seed data is loaded, it will be
   // used immediately so it won't need to be stored.
   chrome_variations::TrialsSeed variations_seed_;
 };
 
 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_SERVICE_H_