More instrumentation to diagnose an Android renderer crash.

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 4d4fdcebde56b38bec2acb8a44679c61d3bd65aa..b5dea9b3628c3f9a5fc347949651387e089684ac 100644
--- a/base/metrics/field_trial.cc
+++ b/base/metrics/field_trial.cc
@@ -10,6 +10,7 @@
 #include "base/lazy_instance.h"
 #include "base/logging.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"
@@ -123,8 +124,14 @@ void CheckTrialGroup(const std::string& trial_name,
 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;
+
 // Tracks whether |g_seen_states| is used. Defaults to false, because unit tests
-// will create multiple FieldTrialList instances.
+// 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
@@ -262,6 +269,9 @@ 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() {}
@@ -356,6 +366,11 @@ void FieldTrialList::EnableGlobalStateChecks() {
 }
 
 // static
+int32_t FieldTrialList::GetDebugToken() {
+  return g_debug_token;
+}
+
+// static
 FieldTrial* FieldTrialList::FactoryGetFieldTrial(
     const std::string& trial_name,
     FieldTrial::Probability total_probability,
@@ -484,6 +499,12 @@ void FieldTrialList::StatesToString(std::string* output) {
     output->append(it->group_name);
     output->append(1, kPersistentStringSeparator);
   }
+  if (g_use_global_check_states) {
+    output->append("DebugToken");
+    output->append(1, kPersistentStringSeparator);
+    output->append(IntToString(g_debug_token));
+    output->append(1, kPersistentStringSeparator);
+  }
 }
 
 // static