Hide ProjectControl.isHidden

This is now only used by the PermissionBackend.ForProject glue code,
and can be marked private.

Change-Id: Ic2fb4d24dde3d2876c5245cb2f3578ea943d75ab
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectControl.java b/gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectControl.java
index 196dcef..74780af 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectControl.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectControl.java
@@ -245,7 +245,7 @@
   }
 
   /** Returns whether the project is hidden. */
-  public boolean isHidden() {
+  private boolean isHidden() {
     return getProject().getState().equals(com.google.gerrit.extensions.client.ProjectState.HIDDEN);
   }