Specify the trial name when crashing due to missing default group name.

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"
@@ skipping 396 matching lines @@
       accumulated_group_probability_(0),
       next_group_number_(kDefaultGroupNumber + 1),
       group_(kNotFinalized),
       enable_field_trial_(true),
       forced_(false),
       group_reported_(false),
       trial_registered_(false),
       ref_(FieldTrialList::FieldTrialAllocator::kReferenceNull) {
   DCHECK_GT(total_probability, 0);
   DCHECK(!trial_name_.empty());
-  DCHECK(!default_group_name_.empty());
+  DCHECK(!default_group_name_.empty())
+      << "Trial " << trial_name << " is missing a default group name.";
 }
 
 FieldTrial::~FieldTrial() {}
 
 void FieldTrial::SetTrialRegistered() {
   DCHECK_EQ(kNotFinalized, group_);
   DCHECK(!trial_registered_);
   trial_registered_ = true;
 }
 
@@ skipping 930 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