Remove traces of removed Mac/Win GN builders.

scripts/slave/recipe_modules/chromium_tests/chromium_mac.py

Index: scripts/slave/recipe_modules/chromium_tests/chromium_mac.py
diff --git a/scripts/slave/recipe_modules/chromium_tests/chromium_mac.py b/scripts/slave/recipe_modules/chromium_tests/chromium_mac.py
index ece170b454193f65912b3d9dfa701657684f792e..63df13cd63ef2870008d70e76df8cf62c604d0be 100644
--- a/scripts/slave/recipe_modules/chromium_tests/chromium_mac.py
+++ b/scripts/slave/recipe_modules/chromium_tests/chromium_mac.py
@@ -101,25 +101,6 @@ SPEC = {
         'platform': 'mac',
       },
     },
-    'Mac GN': {
-      # TODO(dpranke): Remove after builders have restarted.
-      'chromium_config': 'chromium',
-      'chromium_apply_config': ['mb', 'force_mac_toolchain'],
-      'gclient_config': 'chromium',
-      'chromium_config_kwargs': {
-        'BUILD_CONFIG': 'Release',
-        'TARGET_PLATFORM': 'mac',
-      },
-      'test_generators': [
-        steps.generate_gtest,
-        steps.generate_script,
-        steps.generate_isolated_script,
-      ],
-      'enable_swarming': True,
-      'testing': {
-        'platform': 'mac',
-      },
-    },
     'Mac GYP': {
       'chromium_config': 'chromium',
       'chromium_apply_config': ['mb', 'force_mac_toolchain'],
@@ -183,25 +164,6 @@ SPEC = {
         'os': 'Mac-10.9',
       },
     },
-    'Mac GN (dbg)': {
-      # TODO(dpranke): Remove after builders have restarted.
-      'chromium_config': 'chromium',
-      'chromium_apply_config': ['mb', 'force_mac_toolchain'],
-      'gclient_config': 'chromium',
-      'chromium_config_kwargs': {
-        'BUILD_CONFIG': 'Debug',
-        'TARGET_PLATFORM': 'mac',
-      },
-      'test_generators': [
-        steps.generate_gtest,
-        steps.generate_script,
-        steps.generate_isolated_script,
-      ],
-      'enable_swarming': True,
-      'testing': {
-        'platform': 'mac',
-      },
-    },
     'Mac GYP (dbg)': {
       'chromium_config': 'chromium',
       'chromium_apply_config': ['mb', 'force_mac_toolchain'],