Track down Contexts without data directories.

Data directories for all packages should be created and managed by
installd; if we create a Context and the data directory doesn't exist
yet, we're in trouble, since a later mkdirs() would end up creating
the directory with incorrect permissions, mode, and SELinux labels.

Bug: 28272737
Change-Id: Ie3bb884ab07748719378de5c792046a031a3f945

core/java/android/app/ContextImpl.java

@@ -1958,6 +1958,10 @@ class ContextImpl extends Context {
             }
 
             if (res != null) {
+                if (!res.exists()) {
+                    Log.wtf(TAG, "Data directory doesn't exist for package " + getPackageName(),
+                            new Throwable());
+                }
                 return res;
             } else {
                 throw new RuntimeException(