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

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 75832654facebcfa48b91c3fcdffd6caf8a44aa9..d16d79f2455243a9dd77887aac7ef07b77d7a7ef 100644
--- a/base/metrics/field_trial.cc
+++ b/base/metrics/field_trial.cc
@@ -10,6 +10,7 @@
 #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"
@@ -982,6 +983,15 @@ void FieldTrialList::NotifyFieldTrialGroupSelection(FieldTrial* field_trial) {
       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());