Make some field trials unforceable via command-line in the official build.

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 "base/build_time.h"
 #include "base/logging.h"
@@ skipping 381 matching lines @@
 
   for (RegistrationMap::iterator it = global_->registered_.begin();
        it != global_->registered_.end(); ++it) {
     FieldTrial::ActiveGroup active_group;
     if (it->second->GetActiveGroup(&active_group))
       active_groups->push_back(active_group);
   }
 }
 
 // static
-bool FieldTrialList::CreateTrialsFromString(const std::string& trials_string,
-                                            FieldTrialActivationMode mode) {
+bool FieldTrialList::CreateTrialsFromString(
+    const std::string& trials_string,
+    FieldTrialActivationMode mode,
+    const std::set<std::string>& ignored_trial_names) {
   DCHECK(global_);
   if (trials_string.empty() || !global_)
     return true;
 
   size_t next_item = 0;
   while (next_item < trials_string.length()) {
     size_t name_end = trials_string.find(kPersistentStringSeparator, next_item);
     if (name_end == trials_string.npos || next_item == name_end)
       return false;
     size_t group_name_end = trials_string.find(kPersistentStringSeparator,
                                                name_end + 1);
     if (group_name_end == trials_string.npos || name_end + 1 == group_name_end)
       return false;
     std::string name(trials_string, next_item, name_end - next_item);
     std::string group_name(trials_string, name_end + 1,
                            group_name_end - name_end - 1);
     next_item = group_name_end + 1;
 
+    if (ignored_trial_names.find(name) != ignored_trial_names.end())
+      continue;
+
     FieldTrial* trial = CreateFieldTrial(name, group_name);
     if (!trial)
       return false;
     if (mode == ACTIVATE_TRIALS) {
       // Call |group()| to mark the trial as "used" and notify observers, if
       // any. This is useful to ensure that field trials created in child
       // processes are properly reported in crash reports.
       trial->group();
     }
   }
@@ skipping 94 matching lines @@
     return;
   }
   AutoLock auto_lock(global_->lock_);
   DCHECK(!global_->PreLockedFind(trial->trial_name()));
   trial->AddRef();
   trial->SetTrialRegistered();
   global_->registered_[trial->trial_name()] = trial;
 }
 
 }  // namespace base