Updating src side json Mac 10.10 tests to be Mac 10.12

tools/perf/generate_perf_json.py

 #!/usr/bin/env python
 # Copyright 2016 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.
 
 """Script to generate chromium.perf.json and chromium.perf.fyi.json in
 the src/testing/buildbot directory. Maintaining these files by hand is
 too unwieldy.
 """
 
@@ skipping 338 matching lines @@
       {
        'gpu': '8086:0166',
        'os': 'Mac-10.11',
        'device_ids': [
            'build102-b1', 'build103-b1',
            'build104-b1', 'build105-b1', 'build106-b1'
           ]
       }
     ])
   waterfall = add_tester(
-    waterfall, 'Mac 10.10 Perf', 'chromium-rel-mac10',
+    waterfall, 'Mac 10.12 Perf', 'chromium-rel-mac12',
     'mac',
     swarming=[
       {
-       'os': 'Mac-10.10',
+       'os': 'Mac-10.12',
        'gpu': '8086:0a2e',
        'device_ids': [
            'build158-m1', 'build159-m1', 'build160-m1',
            'build161-m1', 'build162-m1']
       }
     ])
   waterfall = add_tester(
     waterfall, 'Mac Retina Perf',
     'chromium-rel-mac-retina', 'mac',
     swarming=[
@@ skipping 365 matching lines @@
   waterfall['name'] = 'chromium.perf'
   fyi_waterfall = get_fyi_waterfall_config()
   fyi_waterfall['name'] = 'chromium.perf.fyi'
 
   generate_all_tests(fyi_waterfall)
   generate_all_tests(waterfall)
   return 0
 
 if __name__ == '__main__':
   sys.exit(main())