Add a fuchsia trybot entry to mb_config.pyl.

tools/mb/mb_config.pyl

 # Copyright 2015 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.
 
 # This is a .pyl, or "Python Literal", file. You can treat it just like a
 # .json file, with the following exceptions:
 # * all keys must be quoted (use single quotes, please);
 # * comments are allowed, using '#' syntax; and
 # * trailing commas are allowed.
 
@@ skipping 495 matching lines @@
 
     'tryserver.chromium.linux': {
       'Chromium Linux Codesearch Builder': 'codesearch',
       'ChromiumOS Codesearch Builder': 'codesearch',
       'cast_shell_linux': 'cast_release_trybot',
       'cast_shell_audio_linux': 'cast_audio_release_trybot',
       'chromeos_amd64-generic_chromium_compile_only_ng': 'cros_chrome_sdk',
       'chromeos_daisy_chromium_compile_only_ng': 'cros_chrome_sdk',
       'chromeos_x86-generic_chromium_compile_only_ng': 'cros_chrome_sdk',
       'closure_compilation': 'closure_compilation',
+      'fuchsia': 'release_trybot_fuchsia',
       'linux_arm': 'release_trybot_arm',
       'linux_chromium_archive_rel_ng': 'release_bot',
       'linux_chromium_asan_rel_ng': 'asan_lsan_release_trybot',
       'linux_chromium_browser_side_navigation_rel': 'release_trybot',
       'linux_chromium_cfi_rel_ng': 'cfi_full_release_static_dcheck_always_on',
       'linux_chromium_chromeos_asan_rel_ng': 'asan_lsan_chromeos_release_trybot',
       'linux_chromium_chromeos_compile_dbg_ng': 'chromeos_with_codecs_debug_trybot',
       'linux_chromium_chromeos_compile_rel_ng': 'chromeos_with_codecs_release_trybot',
       'linux_chromium_chromeos_dbg_ng': 'chromeos_with_codecs_debug_trybot',
       'linux_chromium_chromeos_msan_rel_ng': 'chromeos_msan_release_bot',
@@ skipping 905 matching lines @@
     ],
 
     'release_trybot_minimal_symbols': [
       'release_trybot', 'minimal_symbols',
     ],
 
     'release_trybot_arm': [
       'release_trybot', 'arm',
     ],
 
+    'release_trybot_fuchsia': [
+      'release_trybot', 'fuchsia',
+    ],
+
     'release_trybot_x86': [
       'release_trybot', 'x86',
     ],
 
     'shared_release_bot_x86': [
       'shared_release_bot', 'x86',
     ],
 
     'syzyasan_no_pch_release_x86': [
       'syzyasan', 'no_pch', 'release', 'x86',
@@ skipping 460 matching lines @@
 
     'x64': {
       'gn_args': 'target_cpu="x64"',
     },
 
     'x86': {
       'gn_args': 'target_cpu="x86"',
     },
   },
 }