Add a cast audio bot.

This exercises the is_cast_audio_only=true and enable_webrtc=false
codepaths which periodically break because they are not built.

Corresponding CL at https://chromium-review.googlesource.com/c/452802/

BUG=667546
TEST=`gn gen out_audio/ --args='is_chromecast=true
is_cast_audio_only=true enable_webrtc=false' && ninja -C out_audio/
cast_shell`

Review-Url: https://codereview.chromium.org/2538883003
Cr-Commit-Position: refs/heads/master@{#456222}

testing/buildbot/chromium.linux.json

@@ -2482,6 +2482,175 @@
       }
     ]
   },
+  "Cast Audio Linux": {
+    "gtest_tests": [
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "base_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "cacheinvalidation_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "capture_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "cast_alsa_cma_backend_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "cast_base_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "cast_crash_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "cast_media_unittests"
+      },
+      {
+        "args": [
+          "--enable-local-file-accesses",
+          "--ozone-platform=cast",
+          "--no-sandbox",
+          "--test-launcher-jobs=1"
+        ],
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "cast_shell_browsertests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "cast_shell_unittests"
+      },
+      {
+        "args": [
+          "--test-launcher-filter-file=src/testing/buildbot/filters/cast-linux.content_browsertests.filter"
+        ],
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "content_browsertests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "content_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "crypto_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "gpu_ipc_service_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "gpu_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "ipc_tests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "jingle_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "media_blink_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "media_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "midi_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "net_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "ppapi_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "sandbox_linux_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "sql_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "storage_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "ui_base_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "url_unittests"
+      }
+    ]
+  },
   "Cast Linux": {
     "gtest_tests": [
       {

tools/mb/mb_config.pyl

@@ -266,6 +266,7 @@
       'Android Tests': 'android_release_bot_minimal_symbols',
       'Cast Android (dbg)': 'android_cast_debug_static_bot',
       'Cast Linux': 'cast_release_bot',
+      'Cast Audio Linux': 'cast_audio_release_bot',
       'Linux Builder (dbg)': 'debug_bot',
       'Linux Builder (dbg)(32)': 'debug_bot_x86',
       'Linux Builder': 'release_bot',
@@ -539,6 +540,7 @@
       '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',
@@ -982,6 +984,14 @@
       'cast', 'release_trybot',
     ],
 
+    'cast_audio_release_bot': [
+      'cast', 'cast_audio', 'release_bot',
+    ],
+
+    'cast_audio_release_trybot': [
+      'cast', 'cast_audio', 'release_trybot',
+    ],
+
     'cfi_full_cfi_diag_release_static': [
       'cfi_full', 'cfi_diag', 'release', 'static',
     ],
@@ -1578,6 +1588,10 @@
       'gn_args': 'is_chromecast=true',
     },
 
+    'cast_audio': {
+      'gn_args': 'is_cast_audio_only=true enable_webrtc=false'
+    },
+
     'cfi': {
       'gn_args': 'is_cfi=true',
     },