Add android_webview_unittests to Android GN bot

testing/buildbot/chromium.linux.json

 {
   "Android GN": {
     "additional_compile_targets": [
       "all"
     ],
     "gtest_tests": [
       {
+        "test": "android_webview_unittests"
+      },
+      {
         "test": "base_unittests"
       },
       {
         "test": "blimp_unittests"
       },
       {
         "test": "cc_unittests"
       },
       {
         "test": "components_browsertests"
@@ skipping 1402 matching lines @@
       }
     ],
     "scripts": [
       {
         "name": "nacl_integration",
         "script": "nacl_integration.py"
       }
     ]
   }
 }