Record field-trial information in stability file for crash analysis.

base/metrics/field_trial.cc

 // 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.
 
 #include "base/metrics/field_trial.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/base_switches.h"
 #include "base/build_time.h"
 #include "base/command_line.h"
+#include "base/debug/activity_tracker.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial_param_associator.h"
 #include "base/process/memory.h"
 #include "base/rand_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 
 // On POSIX, the fd is shared using the mapping in GlobalDescriptors.
@@ skipping 952 matching lines @@
       return;
     field_trial->group_reported_ = true;
 
     if (!field_trial->enable_field_trial_)
       return;
 
     if (kUseSharedMemoryForFieldTrials)
       ActivateFieldTrialEntryWhileLocked(field_trial);
   }
 
+  // Recording for stability debugging has to be done inline as a task posted
+  // to an observer may not get executed before a crash.
+  base::debug::GlobalActivityTracker* tracker =
+      base::debug::GlobalActivityTracker::Get();
+  if (tracker) {
+    tracker->RecordFieldTrial(field_trial->trial_name(),
+                              field_trial->group_name_internal());
+  }

[Alexei Svitkine (slow), 2017/02/07 21:23:52]

Nit: I prefer this extra logic to be inside GlobalActivityTracker - i.e. still
have a single static call from here like before and then do the null check
within it and call the instance method there.

The instance method can then be private.

[bcwhite, 2017/02/07 22:09:02]

It could but all the existing tracker interface operates as methods off of an
instance so I'd like to remain consistent with that.

+
   global_->observer_list_->Notify(
       FROM_HERE, &FieldTrialList::Observer::OnFieldTrialGroupFinalized,
       field_trial->trial_name(), field_trial->group_name_internal());
 }
 
 // static
 size_t FieldTrialList::GetFieldTrialCount() {
   if (!global_)
     return 0;
   AutoLock auto_lock(global_->lock_);
@@ skipping 352 matching lines @@
     return;
   }
   AutoLock auto_lock(global_->lock_);
   CHECK(!global_->PreLockedFind(trial->trial_name())) << trial->trial_name();
   trial->AddRef();
   trial->SetTrialRegistered();
   global_->registered_[trial->trial_name()] = trial;
 }
 
 }  // namespace base