Fix getting initially active trials with shared memory.

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 149 matching lines @@
         return false;
       next_item++;
       entry.activated = true;
     }
     entry.trial_name =
         trials_string_piece.substr(next_item, name_end - next_item);
     entry.group_name =
         trials_string_piece.substr(name_end + 1, group_name_end - name_end - 1);
     next_item = group_name_end + 1;
 
-    entries->push_back(entry);
+    entries->push_back(std::move(entry));
   }
   return true;
 }
 
 void AddForceFieldTrialsFlag(CommandLine* cmd_line) {
   std::string field_trial_states;
   FieldTrialList::AllStatesToString(&field_trial_states);
   if (!field_trial_states.empty()) {
     cmd_line->AppendSwitchASCII(switches::kForceFieldTrials,
                                 field_trial_states);
@@ skipping 437 matching lines @@
     if (entry.activated) {
       FieldTrial::ActiveGroup group;
       group.trial_name = entry.trial_name.as_string();
       group.group_name = entry.group_name.as_string();
       active_groups->push_back(group);
     }
   }
 }
 
 // static
+void FieldTrialList::GetInitiallyActiveFieldTrials(
+    const base::CommandLine& command_line,
+    FieldTrial::ActiveGroups* active_groups) {
+  DCHECK(global_->create_trials_from_command_line_called_);
+
+  if (!global_->field_trial_allocator_) {
+    GetActiveFieldTrialGroupsFromString(
+        command_line.GetSwitchValueASCII(switches::kForceFieldTrials),
+        active_groups);
+    return;
+  }
+
+  SharedPersistentMemoryAllocator* allocator =

[lawrencewu, 2016/11/21 20:53:18]

nit: use the FieldTrialAllocator typedef (and below)

[Alexei Svitkine (slow), 2016/11/21 21:11:19]

Done.

+      global_->field_trial_allocator_.get();
+  PersistentMemoryAllocator::Iterator mem_iter(allocator);
+  SharedPersistentMemoryAllocator::Reference ref;

[lawrencewu, 2016/11/21 20:53:18]

FieldTrial::FieldTrialRef ref;

[Alexei Svitkine (slow), 2016/11/21 21:11:19]

Done.

+  while ((ref = mem_iter.GetNextOfType(kFieldTrialType)) !=
+         SharedPersistentMemoryAllocator::kReferenceNull) {
+    const FieldTrialEntry* entry =
+        allocator->GetAsObject<const FieldTrialEntry>(ref, kFieldTrialType);
+
+    StringPiece trial_name;
+    StringPiece group_name;
+    if (entry->activated &&
+        entry->GetTrialAndGroupName(&trial_name, &group_name)) {
+      FieldTrial::ActiveGroup group;
+      group.trial_name = trial_name.as_string();
+      group.group_name = group_name.as_string();
+      active_groups->push_back(group);
+    }
+  }
+}
+
+// static
 bool FieldTrialList::CreateTrialsFromString(
     const std::string& trials_string,
     const std::set<std::string>& ignored_trial_names) {
   DCHECK(global_);
   if (trials_string.empty() || !global_)
     return true;
 
   std::vector<FieldTrial::State> entries;
   if (!ParseFieldTrialsString(trials_string, &entries))
     return false;
@@ skipping 15 matching lines @@
       trial->group();
     }
   }
   return true;
 }
 
 // static
 void FieldTrialList::CreateTrialsFromCommandLine(
     const CommandLine& cmd_line,
     const char* field_trial_handle_switch) {
-  DCHECK(global_);
+  global_->create_trials_from_command_line_called_ = true;
 
 #if defined(OS_WIN) && !defined(OS_NACL)
   if (cmd_line.HasSwitch(field_trial_handle_switch)) {
     std::string arg = cmd_line.GetSwitchValueASCII(field_trial_handle_switch);
     size_t token = arg.find(",");
     int field_trial_handle = std::stoi(arg.substr(0, token));
     size_t field_trial_length = std::stoi(arg.substr(token + 1, arg.length()));
 
     HANDLE handle = reinterpret_cast<HANDLE>(field_trial_handle);
     SharedMemoryHandle shm_handle =
@@ skipping 341 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