Fix getting initially active trials with shared memory.

base/metrics/field_trial.h

 // 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.
 
 // FieldTrial is a class for handling details of statistical experiments
 // performed by actual users in the field (i.e., in a shipped or beta product).
 // All code is called exclusively on the UI thread currently.
 //
 // The simplest example is an experiment to see whether one of two options
 // produces "better" results across our user population.  In that scenario, UMA
@@ skipping 452 matching lines @@
   // has been chosen and externally observed (via |group()|) and which have
   // not been disabled.
   static void GetActiveFieldTrialGroups(
       FieldTrial::ActiveGroups* active_groups);
 
   // Returns the field trials that are marked active in |trials_string|.
   static void GetActiveFieldTrialGroupsFromString(
       const std::string& trials_string,
       FieldTrial::ActiveGroups* active_groups);
 
+  // Returns the field trials that were active when the process was
+  // created. Either parses the field trial string or the shared memory
+  // holding field trial information.
+  // Must be called only after a call to CreateTrialsFromCommandLine().
+  static void GetInitiallyActiveFieldTrials(
+      const base::CommandLine& command_line,
+      FieldTrial::ActiveGroups* active_groups);
+
   // Use a state string (re: StatesToString()) to augment the current list of
   // field trials to include the supplied trials, and using a 100% probability
   // for each trial, force them to have the same group string. This is commonly
   // used in a non-browser process, to carry randomly selected state in a
   // browser process into this non-browser process, but could also be invoked
   // through a command line argument to the browser process. Created field
   // trials will be marked "used" for the purposes of active trial reporting
   // if they are prefixed with |kActivationMarker|. Trial names in
   // |ignored_trial_names| are ignored when parsing |trials_string|.
   static bool CreateTrialsFromString(
@@ skipping 131 matching lines @@
   // to start passing more data other than field trials.
   std::unique_ptr<FieldTrialAllocator> field_trial_allocator_ = nullptr;
 
 #if defined(OS_WIN)
   // Readonly copy of the handle to the allocator. Needs to be a member variable
   // because it's needed from both CopyFieldTrialStateToFlags() and
   // AppendFieldTrialHandleIfNeeded().
   HANDLE readonly_allocator_handle_ = nullptr;
 #endif
 
+  // Tracks whether CreateTrialsFromCommandLine() has been called.
+  bool create_trials_from_command_line_called_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(FieldTrialList);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_FIELD_TRIAL_H_