Add contact and key sync message receive support.

app/src/main/java/org/thoughtcrime/securesms/providers/BlobProvider.java

@@ -413,6 +413,19 @@ public class BlobProvider {
     return context.getDir(directory, Context.MODE_PRIVATE);
   }
 
+  /**
+   * Returns a {@link File} within the appropriate directory to be cleaned up as part of
+   * normal operations. Unlike other blobs, this is just a file reference and no
+   * automatic encryption occurs when reading or writing and must be done by the caller.
+   *
+   * @return file located in the appropriate directory to be delete on app session restarts
+   */
+  public File forNonAutoEncryptingSingleSessionOnDisk(@NonNull Context context) {
+    String directory = getDirectory(StorageType.SINGLE_SESSION_DISK);
+    String id        = UUID.randomUUID().toString();
+    return new File(getOrCreateDirectory(context, directory), buildFileName(id));
+  }
+
   public class BlobBuilder {
 
     private InputStream data;