BASELINE: Update Chromium to 85.0.4183.14085-based

Change-Id: Iaa42f4680837c57725b1344f108c0196741f6057
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 114 insertions, 28 deletions

diff --git a/chromium/components/variations/synthetic_trial_registry.cc b/chromium/components/variations/synthetic_trial_registry.cc
index ea07f680fbd..c0afd33c474 100644
--- a/chromium/components/variations/synthetic_trial_registry.cc
+++ b/chromium/components/variations/synthetic_trial_registry.cc
@@ -4,11 +4,32 @@
 
 #include "components/variations/synthetic_trial_registry.h"
 
+#include <algorithm>
+
+#include "base/metrics/histogram_functions.h"
 #include "base/stl_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "components/variations/hashing.h"
+#include "components/variations/variations_associated_data.h"
 
 namespace variations {
+namespace internal {
+
+const base::Feature kExternalExperimentAllowlist{
+    "ExternalExperimentAllowlist", base::FEATURE_ENABLED_BY_DEFAULT};
+
+}  // namespace internal
 
-SyntheticTrialRegistry::SyntheticTrialRegistry() = default;
+SyntheticTrialRegistry::SyntheticTrialRegistry(
+    bool enable_external_experiment_allowlist)
+    : enable_external_experiment_allowlist_(
+          enable_external_experiment_allowlist &&
+          base::FeatureList::IsEnabled(
+              internal::kExternalExperimentAllowlist)) {}
+
+SyntheticTrialRegistry::SyntheticTrialRegistry()
+    : enable_external_experiment_allowlist_(base::FeatureList::IsEnabled(
+          internal::kExternalExperimentAllowlist)) {}
 SyntheticTrialRegistry::~SyntheticTrialRegistry() = default;
 
 void SyntheticTrialRegistry::AddSyntheticTrialObserver(
@@ -23,13 +44,78 @@ void SyntheticTrialRegistry::RemoveSyntheticTrialObserver(
   synthetic_trial_observer_list_.RemoveObserver(observer);
 }
 
+void SyntheticTrialRegistry::RegisterExternalExperiments(
+    const std::string& fallback_study_name,
+    const std::vector<int>& experiment_ids,
+    SyntheticTrialRegistry::OverrideMode mode) {
+  DCHECK(!fallback_study_name.empty());
+
+  base::FieldTrialParams params;
+  if (enable_external_experiment_allowlist_ &&
+      !GetFieldTrialParamsByFeature(internal::kExternalExperimentAllowlist,
+                                    &params)) {
+    return;
+  }
+
+  // When overriding previous external experiments, remove them now.
+  if (mode == kOverrideExistingIds) {
+    auto is_external = [](const SyntheticTrialGroup& group) {
+      return group.is_external;
+    };
+    base::EraseIf(synthetic_trial_groups_, is_external);
+  }
+
+  const base::TimeTicks start_time = base::TimeTicks::Now();
+  int trials_added = 0;
+  for (int experiment_id : experiment_ids) {
+    const std::string experiment_id_str = base::NumberToString(experiment_id);
+    const base::StringPiece study_name =
+        GetStudyNameForExpId(fallback_study_name, params, experiment_id_str);
+    if (study_name.empty())
+      continue;
+
+    const uint32_t trial_hash = HashName(study_name);
+    // If existing ids shouldn't be overridden, skip entries whose study names
+    // are already registered.
+    if (mode == kDoNotOverrideExistingIds) {
+      auto matches_trial = [trial_hash](const SyntheticTrialGroup& group) {
+        return group.id.name == trial_hash;
+      };
+      const auto& groups = synthetic_trial_groups_;
+      if (std::any_of(groups.begin(), groups.end(), matches_trial)) {
+        continue;
+      }
+    }
+
+    const uint32_t group_hash = HashName(experiment_id_str);
+
+    // Since external experiments are not based on Chrome's low entropy source,
+    // they are only sent to Google web properties for signed-in users to make
+    // sure they couldn't be used to identify a user that's not signed-in.
+    AssociateGoogleVariationIDForceHashes(
+        GOOGLE_WEB_PROPERTIES_SIGNED_IN, {trial_hash, group_hash},
+        static_cast<VariationID>(experiment_id));
+    SyntheticTrialGroup entry(trial_hash, group_hash);
+    entry.start_time = start_time;
+    entry.is_external = true;
+    synthetic_trial_groups_.push_back(entry);
+    trials_added++;
+  }
+
+  base::UmaHistogramCounts100("UMA.ExternalExperiment.GroupCount",
+                              trials_added);
+
+  if (trials_added > 0)
+    NotifySyntheticTrialObservers();
+}
+
 void SyntheticTrialRegistry::RegisterSyntheticFieldTrial(
     const SyntheticTrialGroup& trial) {
-  for (size_t i = 0; i < synthetic_trial_groups_.size(); ++i) {
-    if (synthetic_trial_groups_[i].id.name == trial.id.name) {
-      if (synthetic_trial_groups_[i].id.group != trial.id.group) {
-        synthetic_trial_groups_[i].id.group = trial.id.group;
-        synthetic_trial_groups_[i].start_time = base::TimeTicks::Now();
+  for (auto& entry : synthetic_trial_groups_) {
+    if (entry.id.name == trial.id.name) {
+      if (entry.id.group != trial.id.group) {
+        entry.id.group = trial.id.group;
+        entry.start_time = base::TimeTicks::Now();
         NotifySyntheticTrialObservers();
       }
       return;
@@ -42,26 +128,26 @@ void SyntheticTrialRegistry::RegisterSyntheticFieldTrial(
   NotifySyntheticTrialObservers();
 }
 
-void SyntheticTrialRegistry::RegisterSyntheticMultiGroupFieldTrial(
-    uint32_t trial_name_hash,
-    const std::vector<uint32_t>& group_name_hashes) {
-  auto has_same_trial_name = [trial_name_hash](const SyntheticTrialGroup& x) {
-    return x.id.name == trial_name_hash;
-  };
-  base::EraseIf(synthetic_trial_groups_, has_same_trial_name);
+base::StringPiece SyntheticTrialRegistry::GetStudyNameForExpId(
+    const std::string& fallback_study_name,
+    const base::FieldTrialParams& params,
+    const std::string& experiment_id) {
+  if (!enable_external_experiment_allowlist_)
+    return fallback_study_name;
 
-  if (group_name_hashes.empty())
-    return;
+  const auto it = params.find(experiment_id);
+  if (it == params.end())
+    return base::StringPiece();
 
-  SyntheticTrialGroup trial_group(trial_name_hash, group_name_hashes[0]);
-  trial_group.start_time = base::TimeTicks::Now();
-  for (uint32_t group_name_hash : group_name_hashes) {
-    // Note: Adding the trial group will copy it, so this re-uses the same
-    // |trial_group| struct for convenience (e.g. so start_time's all match).
-    trial_group.id.group = group_name_hash;
-    synthetic_trial_groups_.push_back(trial_group);
-  }
-  NotifySyntheticTrialObservers();
+  // To support additional parameters being passed, besides the study name,
+  // truncate the study name at the first ',' character.
+  // For example, for an entry like {"1234": "StudyName,FOO"}, we only want the
+  // "StudyName" part. This allows adding support for additional things like FOO
+  // in the future without backwards compatibility problems.
+  const size_t comma_pos = it->second.find(',');
+  const size_t truncate_pos =
+      (comma_pos == std::string::npos ? it->second.length() : comma_pos);
+  return base::StringPiece(it->second.data(), truncate_pos);
 }
 
 void SyntheticTrialRegistry::NotifySyntheticTrialObservers() {
@@ -72,12 +158,12 @@ void SyntheticTrialRegistry::NotifySyntheticTrialObservers() {
 
 void SyntheticTrialRegistry::GetSyntheticFieldTrialsOlderThan(
     base::TimeTicks time,
-    std::vector<ActiveGroupId>* synthetic_trials) {
+    std::vector<ActiveGroupId>* synthetic_trials) const {
   DCHECK(synthetic_trials);
   synthetic_trials->clear();
-  for (size_t i = 0; i < synthetic_trial_groups_.size(); ++i) {
-    if (synthetic_trial_groups_[i].start_time <= time)
-      synthetic_trials->push_back(synthetic_trial_groups_[i].id);
+  for (const auto& entry : synthetic_trial_groups_) {
+    if (entry.start_time <= time)
+      synthetic_trials->push_back(entry.id);
   }
 }