Share field trial allocator on MacOS

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 564 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(FieldTrialListTest, AssociateFieldTrialParams);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialListTest, ClearParamsFromSharedMemory);
 
 #if defined(OS_WIN)
   // Takes in |handle_switch| from the command line which represents the shared
   // memory handle for field trials, parses it, and creates the field trials.
   // Returns true on success, false on failure.
   static bool CreateTrialsFromHandleSwitch(const std::string& handle_switch);
 #endif
 
-#if defined(OS_POSIX) && !defined(OS_NACL) && !defined(OS_MACOSX) && \
-    !defined(OS_ANDROID)
+#if defined(OS_POSIX) && !defined(OS_NACL) && !defined(OS_ANDROID)
   // On POSIX systems that use the zygote, we look up the correct fd that backs
   // the shared memory segment containing the field trials by looking it up via
   // an fd key in GlobalDescriptors. Returns true on success, false on failure.
   static bool CreateTrialsFromDescriptor(int fd_key);
 #endif
 
   // Takes an unmapped SharedMemoryHandle, creates a SharedMemory object from it
   // and maps it with the correct size.
   static bool CreateTrialsFromSharedMemoryHandle(SharedMemoryHandle shm_handle);
 
@@ skipping 67 matching lines @@
 
   // 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_