android: Add entry for 'skia_unittests' to UNIT_TESTS list.

scripts/slave/recipes/android/tester.expected/chromium_linux_Android_Tests.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "chromium.linux",
       "--builder",
       "Android Tests",
@@ skipping 604 matching lines @@
     },
     "name": "sandbox_linux_unittests"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/build/android/test_runner.py",
       "gtest",
       "-s",
+      "skia_unittests",
+      "--verbose",
+      "--release",
+      "--flakiness-dashboard-server=http://test-results.appspot.com"
+    ],
+    "env": {
+      "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
+    },
+    "name": "skia_unittests"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "[SLAVE_BUILD]/src/build/android/test_runner.py",
+      "gtest",
+      "-s",
       "sql_unittests",
       "--verbose",
       "--release",
       "--flakiness-dashboard-server=http://test-results.appspot.com"
     ],
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "sql_unittests"
   },
@@ skipping 147 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import glob, os, sys@@@",
       "@@@STEP_LOG_LINE@python.inline@for report in glob.glob(sys.argv[1]):@@@",
       "@@@STEP_LOG_LINE@python.inline@  with open(report, 'r') as f:@@@",
       "@@@STEP_LOG_LINE@python.inline@    for l in f.readlines():@@@",
       "@@@STEP_LOG_LINE@python.inline@      print l@@@",
       "@@@STEP_LOG_LINE@python.inline@  os.remove(report)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   }
-]
+]