Fix adding duplicate trials to allocator (finally)

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 525 matching lines @@
   // Notify all observers that a group has been finalized for |field_trial|.
   static void NotifyFieldTrialGroupSelection(FieldTrial* field_trial);
 
   // Return the number of active field trials.
   static size_t GetFieldTrialCount();
 
  private:
   // Allow tests to access our innards for testing purposes.
   FRIEND_TEST_ALL_PREFIXES(FieldTrialListTest, InstantiateAllocator);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialListTest, AddTrialsToAllocator);
+  FRIEND_TEST_ALL_PREFIXES(FieldTrialListTest,
+                           DoNotAddSimulatedFieldTrialsToAllocator);
 
 #if defined(OS_WIN)
   // Takes in |handle| that should have been retrieved from the command line and
   // creates a SharedMemoryHandle from it, and then calls
   // CreateTrialsFromSharedMemory(). Returns true on success, false on failure.
   static bool CreateTrialsFromWindowsHandle(HANDLE handle);
 #endif
 
   // Expects a mapped piece of shared memory |shm| that was created from the
   // browser process's field_trial_allocator and shared via the command line.
@@ skipping 64 matching lines @@
   // AppendFieldTrialHandleIfNeeded().
   HANDLE readonly_allocator_handle_ = nullptr;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(FieldTrialList);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_FIELD_TRIAL_H_