Remove debug instrumentation for crbug.com/359406.

base/metrics/field_trial.cc

Index: base/metrics/field_trial.cc
diff --git a/base/metrics/field_trial.cc b/base/metrics/field_trial.cc
index 3b398cd20e793401ee1f73d914b7f5b393fce6da..430cae0b7287d1c3f400ad64afdc272b3a4fd0dc 100644
--- a/base/metrics/field_trial.cc
+++ b/base/metrics/field_trial.cc
@@ -7,7 +7,6 @@
 #include <algorithm>
 
 #include "base/build_time.h"
-#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "base/strings/string_number_conversions.h"
@@ -107,38 +106,6 @@ bool ParseFieldTrialsString(const std::string& trials_string,
   return true;
 }
 
-void CheckTrialGroup(const std::string& trial_name,
-                     const std::string& trial_group,
-                     std::map<std::string, std::string>* seen_states) {
-  if (ContainsKey(*seen_states, trial_name)) {
-    CHECK_EQ((*seen_states)[trial_name], trial_group) << trial_name;
-  } else {
-    (*seen_states)[trial_name] = trial_group;
-  }
-}
-
-// A second copy of FieldTrialList::seen_states_ that is meant to outlive the
-// FieldTrialList object to determine if the inconsistency happens because there
-// might be multiple FieldTrialList objects.
-// TODO(asvitkine): Remove when crbug.com/359406 is resolved.
-base::LazyInstance<std::map<std::string, std::string>>::Leaky g_seen_states =
-    LAZY_INSTANCE_INITIALIZER;
-
-// A debug token generated during FieldTrialList construction. Used to diagnose
-// crbug.com/359406.
-// TODO(asvitkine): Remove when crbug.com/359406 is resolved.
-int32_t g_debug_token = -1;
-
-// Whether to append the debug token to the child process --force-fieldtrials
-// command line. Used to diagnose crbug.com/359406.
-// TODO(asvitkine): Remove when crbug.com/359406 is resolved.
-bool g_append_debug_token_to_trial_string = false;
-
-// Tracks whether |g_seen_states| is used. Defaults to false, because unit tests
-// will create multiple FieldTrialList instances. Also controls whether
-// |g_debug_token| is included in the field trial state string.
-bool g_use_global_check_states = false;
-
 }  // namespace
 
 // statics
@@ -242,9 +209,7 @@ void FieldTrial::SetForced() {
 
 // static
 void FieldTrial::EnableBenchmarking() {
-  // TODO(asvitkine): Change this back to 0u after the trial in FieldTrialList
-  // constructor is removed.
-  DCHECK_EQ(1u, FieldTrialList::GetFieldTrialCount());
+  DCHECK_EQ(0u, FieldTrialList::GetFieldTrialCount());
   enable_benchmarking_ = true;
 }
 
@@ -276,9 +241,6 @@ FieldTrial::FieldTrial(const std::string& trial_name,
   DCHECK_GT(total_probability, 0);
   DCHECK(!trial_name_.empty());
   DCHECK(!default_group_name_.empty());
-
-  if (g_debug_token == -1)
-    g_debug_token = RandInt(1, INT32_MAX);
 }
 
 FieldTrial::~FieldTrial() {}
@@ -344,8 +306,7 @@ FieldTrialList::FieldTrialList(
     : entropy_provider_(entropy_provider),
       observer_list_(new ObserverListThreadSafe<FieldTrialList::Observer>(
           ObserverListBase<FieldTrialList::Observer>::NOTIFY_EXISTING_ONLY)) {
-  // TODO(asvitkine): Turn into a DCHECK after http://crbug.com/359406 is fixed.
-  CHECK(!global_);
+  DCHECK(!global_);
   DCHECK(!used_without_global_);
   global_ = this;
 
@@ -353,30 +314,6 @@ FieldTrialList::FieldTrialList(
   Time::Exploded exploded;
   two_years_from_build_time.LocalExplode(&exploded);
   kNoExpirationYear = exploded.year;
-
-  // Run a 50/50 experiment that enables |g_use_global_check_states| only for
-  // half the users, to investigate if this instrumentation is causing the
-  // crashes to disappear for http://crbug.com/359406. Done here instead of a
-  // server-side trial because this needs to be done early during FieldTrialList
-  // initialization.
-  //
-  // Note: |g_use_global_check_states| is set via EnableGlobalStateChecks()
-  // prior to the FieldTrialList being created. We only want to do the trial
-  // check once the first time FieldTrialList is created, so use a static
-  // |first_time| variable to track this.
-  //
-  // TODO(asvitkine): Remove after http://crbug.com/359406 is fixed.
-  static bool first_time = true;
-  if (first_time && g_use_global_check_states) {
-    first_time = false;
-    base::FieldTrial* trial =
-        FactoryGetFieldTrial("UMA_CheckStates", 100, "NoChecks",
-                             kNoExpirationYear, 1, 1,
-                             FieldTrial::SESSION_RANDOMIZED, nullptr);
-    trial->AppendGroup("Checks", 50);
-    if (trial->group_name() == "NoChecks")
-      g_use_global_check_states = false;
-  }
 }
 
 FieldTrialList::~FieldTrialList() {
@@ -391,18 +328,6 @@ FieldTrialList::~FieldTrialList() {
 }
 
 // static
-void FieldTrialList::EnableGlobalStateChecks() {
-  CHECK(!g_use_global_check_states);
-  g_use_global_check_states = true;
-  g_append_debug_token_to_trial_string = true;
-}
-
-// static
-int32_t FieldTrialList::GetDebugToken() {
-  return g_debug_token;
-}
-
-// static
 FieldTrial* FieldTrialList::FactoryGetFieldTrial(
     const std::string& trial_name,
     FieldTrial::Probability total_probability,
@@ -534,12 +459,6 @@ void FieldTrialList::StatesToString(std::string* output) {
     output->append(it->group_name);
     output->append(1, kPersistentStringSeparator);
   }
-  if (g_append_debug_token_to_trial_string) {
-    output->append("DebugToken");
-    output->append(1, kPersistentStringSeparator);
-    output->append(IntToString(g_debug_token));
-    output->append(1, kPersistentStringSeparator);
-  }
 }
 
 // static
@@ -562,14 +481,6 @@ void FieldTrialList::AllStatesToString(std::string* output) {
     output->append(1, kPersistentStringSeparator);
     trial.group_name.AppendToString(output);
     output->append(1, kPersistentStringSeparator);
-
-    // TODO(asvitkine): Remove these when http://crbug.com/359406 is fixed.
-    CheckTrialGroup(trial.trial_name.as_string(), trial.group_name.as_string(),
-                    &global_->seen_states_);
-    if (g_use_global_check_states) {
-      CheckTrialGroup(trial.trial_name.as_string(),
-                      trial.group_name.as_string(), &g_seen_states.Get());
-    }
   }
 }
 
@@ -694,16 +605,6 @@ void FieldTrialList::NotifyFieldTrialGroupSelection(FieldTrial* field_trial) {
   if (!field_trial->enable_field_trial_)
     return;
 
-  // TODO(asvitkine): Remove this block when http://crbug.com/359406 is fixed.
-  {
-    AutoLock auto_lock(global_->lock_);
-    CheckTrialGroup(field_trial->trial_name(),
-                    field_trial->group_name_internal(), &global_->seen_states_);
-    if (g_use_global_check_states) {
-      CheckTrialGroup(field_trial->trial_name(),
-                      field_trial->group_name_internal(), &g_seen_states.Get());
-    }
-  }
   global_->observer_list_->Notify(
       FROM_HERE, &FieldTrialList::Observer::OnFieldTrialGroupFinalized,
       field_trial->trial_name(), field_trial->group_name_internal());