Reland "skia: Add 'skia_unittests' test suite for this directory."

testing/buildbot/chromium.webkit.json

 {
   "Linux ChromiumOS Tests (1)": {
     "gtest_tests": [
       "accessibility_unittests",
       {
         "test": "base_unittests",
         "swarming": {
           "can_use_on_swarming_builders": true
         }
       },
@@ skipping 68 matching lines @@
         "test": "unit_tests",
         "swarming": {
           "can_use_on_swarming_builders": true
         }
       },
       "sql_unittests",
       "nacl_loader_unittests",
       "athena_unittests",
       "app_shell_browsertests",
       "app_shell_unittests",
-      "chromevox_tests"
+      "chromevox_tests",
+      "skia_unittests"
     ]
   },
   "Linux ChromiumOS Tests (2)": {
     "gtest_tests": [
     ]
   },
   "Linux ChromiumOS Tests (dbg)(1)": {
     "gtest_tests": [
       "accessibility_unittests",
       {
@@ skipping 67 matching lines @@
       "app_shell_unittests",
       {
         "test": "content_browsertests",
         "swarming": {
           "can_use_on_swarming_builders": true,
           "shards": 2
         }
       },
       "athena_unittests",
       "gcm_unit_tests",
+      "skia_unittests",
       {
         "test": "interactive_ui_tests",
         "swarming": {
           "can_use_on_swarming_builders": true,
           "shards": 3
         }
       }
     ]
   },
   "Linux ChromiumOS Tests (dbg)(2)": {
     "gtest_tests": [
     ]
   },
   "Linux ChromiumOS Tests (dbg)(3)": {
     "gtest_tests": [
     ]
   }
 }