Plumbing for variations headers from synthetic field trials.

components/variations/net/variations_http_header_provider.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_VARIATIONS_NET_VARIATIONS_HTTP_HEADER_PROVIDER_H_
 #define COMPONENTS_VARIATIONS_NET_VARIATIONS_HTTP_HEADER_PROVIDER_H_
 
 #include <set>
 #include <string>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/gtest_prod_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/synchronization/lock.h"
+#include "components/metrics/metrics_service.h"
 #include "components/variations/variations_associated_data.h"
 
 namespace content {
 class ResourceContext;
 }
 
 namespace net {
 class HttpRequestHeaders;
 }
 
 class GURL;
 
 template <typename T> struct DefaultSingletonTraits;
 
 namespace variations {
 
 // A helper class for maintaining client experiments and metrics state
 // transmitted in custom HTTP request headers.
 // This class is a thread-safe singleton.
-class VariationsHttpHeaderProvider : base::FieldTrialList::Observer {
+class VariationsHttpHeaderProvider : public base::FieldTrialList::Observer,
+                                     public metrics::SyntheticTrialObserver {
  public:
   static VariationsHttpHeaderProvider* GetInstance();
 
   // Adds Chrome experiment and metrics state as custom headers to |headers|.
   // Some headers may not be set given the |incognito| mode or whether
   // the user has |uma_enabled|.  Also, we never transmit headers to non-Google
   // sites, which is checked based on the destination |url|.
   void AppendHeaders(const GURL& url,
                      bool incognito,
                      bool uma_enabled,
@@ skipping 14 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(VariationsHttpHeaderProviderTest,
                            SetDefaultVariationIds_Valid);
   FRIEND_TEST_ALL_PREFIXES(VariationsHttpHeaderProviderTest,
                            SetDefaultVariationIds_Invalid);
   FRIEND_TEST_ALL_PREFIXES(VariationsHttpHeaderProviderTest,
                            OnFieldTrialGroupFinalized);
 
   VariationsHttpHeaderProvider();
   ~VariationsHttpHeaderProvider() override;
 
-  // base::FieldTrialList::Observer implementation.
+  // base::FieldTrialList::Observer:
   // This will add the variation ID associated with |trial_name| and
   // |group_name| to the variation ID cache.
   void OnFieldTrialGroupFinalized(const std::string& trial_name,
                                   const std::string& group_name) override;
 
+  // metrics::SyntheticTrialObserver:
+  void OnSyntheticTrialsChanged(
+      const std::vector<metrics::SyntheticTrialGroup>& groups) override;
+
   // Prepares the variation IDs cache with initial values if not already done.
   // This method also registers the caller with the FieldTrialList to receive
   // new variation IDs.
   void InitVariationIDsCacheIfNeeded();
 
   // Takes whatever is currently in |variation_ids_set_| and recreates
   // |variation_ids_header_| with it.  Assumes the the |lock_| is currently
   // held.
   void UpdateVariationIDsHeaderValue();
 
@@ skipping 10 matching lines @@
 
   // Keep a cache of variation IDs that are transmitted in headers to Google.
   // This consists of a list of valid IDs, and the actual transmitted header.
   std::set<VariationID> variation_ids_set_;
   std::set<VariationID> variation_trigger_ids_set_;
 
   // Provides the google experiment ids forced from command line.
   std::set<VariationID> default_variation_ids_set_;
   std::set<VariationID> default_trigger_id_set_;
 
+  // Variations ids from synthetic field trials.
+  std::set<VariationID> synthetic_variation_ids_set_;
+
   std::string variation_ids_header_;
 
   DISALLOW_COPY_AND_ASSIGN(VariationsHttpHeaderProvider);
 };
 
 }  // namespace variations
 
 #endif  // COMPONENTS_VARIATIONS_NET_VARIATIONS_HTTP_HEADER_PROVIDER_H_