Add mediaroutertest to frameworks/base/media/TEST_MAPPING

Bug: 232812007
Change-Id: I283df974d80e61cdf6997b8f58c2ff9e642961d5
Test: N/A. TEST_MAPPING change.
diff --git a/media/TEST_MAPPING b/media/TEST_MAPPING
index 6f0e623..e8c7ad2 100644
--- a/media/TEST_MAPPING
+++ b/media/TEST_MAPPING
@@ -4,6 +4,9 @@
       "name": "CtsMediaBetterTogetherTestCases"
     },
     {
+      "name": "mediaroutertest"
+    },
+    {
       "name": "CtsCameraTestCases",
       "options" : [
         {