Add cast_alsa_cma_backend_unittests to buildbot

testing/buildbot/gn_isolate_map.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.
 
 # gn_isolate_map.pyl - A mapping of Ninja build target names to GN labels and
 # test type classifications for the tests that are run on the bots.
 #
 # This mapping is used by MB so that we can uniformly refer to test binaries
 # by their Ninja target names in the recipes and not need to worry about how
 # they are referred to in GN or GYP specifically (the GYP target name is pretty
@@ skipping 145 matching lines @@
     "label": "//chrome/test:browser_tests",
     "type": "windowed_test_launcher",
   },
   "cacheinvalidation_unittests": {
     "label": "//third_party/cacheinvalidation:cacheinvalidation_unittests",
     "type": "raw",
     "args": [
       "--test-launcher-bot-mode",
     ],
   },
+  "cast_alsa_cma_backend_unittests": {
+    "label": "//chromecast/media/cma/backend/alsa:cast_alsa_cma_backend_unittests",
+    "type": "unknown",
+  },
   "cast_base_unittests": {
     "label": "//cast:cast_base_unittests",
     "type": "unknown",
   },
   "cast_crash_unittests": {
     "label": "//chromecast/crash:cast_crash_unittests",
     "type": "unknown",
   },
   "cast_shell_unittests": {
     "label": "//chromecast/app:cast_shell_unittests",
@@ skipping 409 matching lines @@
   },
   "wm_unittests": {
     "label": "//ui/wm:wm_unittests",
     "type": "windowed_test_launcher",
   },
   "wtf_unittests": {
     "label": "//third_party/WebKit/Source/wtf:wtf_unittests",
     "type": "console_test_launcher",
   },
 }