[Fuchsia] Add mb config for fuchsia code coverage builder.

Bug: 1156885
Change-Id: I7474d2e833a41e6ccbb40828abac9523fcded533
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2581002
Auto-Submit: Chong Gu <chonggu@google.com>
Reviewed-by: Haiyang Pan <hypan@google.com>
Commit-Queue: Haiyang Pan <hypan@google.com>
Cr-Commit-Position: refs/heads/master@{#835042}

tools/mb/mb_config.pyl

@@ -286,6 +286,7 @@
       'android-paeverywhere-arm64-fyi-dbg': 'debug_bot_paeverywhere_arm64',
       'android-paeverywhere-arm64-fyi-rel': 'release_trybot_paeverywhere_arm64',
       'chromeos-amd64-generic-lacros-rel': 'chromeos_amd64-generic_lacros_rel',
+      'fuchsia-code-coverage': 'fuchsia_clang_code_coverage',
       'fuchsia-fyi-arm64-dbg': 'debug_bot_fuchsia_arm64',
       'fuchsia-fyi-arm64-rel': 'release_bot_fuchsia_arm64',
       'fuchsia-fyi-x64-dbg': 'debug_bot_fuchsia',
@@ -1888,6 +1889,10 @@
       'debug_bot', 'x86', 'no_com_init_hooks', 'chrome_with_codecs'
     ],
 
+    'fuchsia_clang_code_coverage': [
+      'fuchsia', 'release_bot', 'clang', 'use_clang_coverage', 'no_symbols'
+    ],
+
     'fuchsia_official_optimize_goma': [
       'official_optimize_goma', 'fuchsia',
     ],

tools/mb/mb_config_expectations/chromium.fyi.json

@@ -315,6 +315,17 @@
       "use_vaapi": false
     }
   },
+  "fuchsia-code-coverage": {
+    "gn_args": {
+      "is_clang": true,
+      "is_component_build": false,
+      "is_debug": false,
+      "symbol_level": 0,
+      "target_os": "fuchsia",
+      "use_clang_coverage": true,
+      "use_goma": true
+    }
+  },
   "fuchsia-fyi-arm64-dbg": {
     "gn_args": {
       "is_component_build": true,