Adding Athenas browser and unit tests which are required for running the tests on a buildbot

testing/buildbot/chromium.chromiumos.json

 {
   "Linux ChromiumOS Tests (1)": {
     "gtest_tests": [
       "accessibility_unittests",
       {
         "test": "base_unittests",
         "swarming": {
           "can_use_on_swarming_builders": true
         }
       },
@@ skipping 74 matching lines @@
       "athena_unittests",
       "app_shell_browsertests",
       "app_shell_unittests",
       "chromevox_tests"
     ]
   },
   "Linux ChromiumOS Tests (2)": {
     "gtest_tests": [
     ]
   },
+  "Linux ChromiumOS Athena Tests (1)": {
+    "gtest_tests": [
+      "athena_unittests",
+      "browser_tests"

[sky, 2014/10/09 17:43:19]

Can these be swarmed?

[Mr4D (OOO till 08-26), 2014/10/09 19:45:14]

Should be the same as chrome. Added.

+    ]
+  },
   "Linux ChromiumOS Ozone Tests (1)": {
     "gtest_tests": [
       "accessibility_unittests",
       "app_list_unittests",
       "app_shell_browsertests",
       "app_shell_unittests",
       "ash_unittests",
       "athena_unittests",
       "aura_unittests",
       "base_unittests",
@@ skipping 129 matching lines @@
   },
   "Linux ChromiumOS Tests (dbg)(2)": {
     "gtest_tests": [
     ]
   },
   "Linux ChromiumOS Tests (dbg)(3)": {
     "gtest_tests": [
     ]
   }
 }