Make change and version bump to r_aml_300900400 for mainline module file: manifest.json

Change-Id: Ib36851f08e16e3c6c366c9a031225ecf1c6feb18
diff --git a/manifest.json b/manifest.json
index 0ab3b41..056ece9 100644
--- a/manifest.json
+++ b/manifest.json
@@ -1,4 +1,4 @@
 {
   "name": "com.android.sdkext",
-  "version": 300900300
+  "version": 300900400
 }