Made --apps-use-native-frame flag available on Mac.

chrome/browser/about_flags.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 "chrome/browser/about_flags.h"
 
 #include <algorithm>
 #include <iterator>
 #include <map>
 #include <set>
@@ skipping 1447 matching lines @@
     "enable-tcp-fast-open",
     IDS_FLAGS_ENABLE_TCP_FAST_OPEN_NAME,
     IDS_FLAGS_ENABLE_TCP_FAST_OPEN_DESCRIPTION,
     kOsLinux | kOsCrOS | kOsAndroid,
     SINGLE_VALUE_TYPE(switches::kEnableTcpFastOpen)
   },
   {
     "apps-use-native-frame",
     IDS_FLAGS_ENABLE_NATIVE_FRAMES_FOR_APPS_NAME,
     IDS_FLAGS_ENABLE_NATIVE_FRAMES_FOR_APPS_DESCRIPTION,
-    kOsWin,
+    kOsMac | kOsWin,
     SINGLE_VALUE_TYPE(switches::kAppsUseNativeFrame)
   },
   {
     "enable-syncfs-directory-operation",
     IDS_FLAGS_ENABLE_SYNC_DIRECTORY_OPERATION_NAME,
     IDS_FLAGS_ENABLE_SYNC_DIRECTORY_OPERATION_DESCRIPTION,
     kOsAll,
     SINGLE_VALUE_TYPE(switches::kSyncfsEnableDirectoryOperation),
   },
   {
@@ skipping 635 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags