Make BaseServlet#newWriter(HttpServletRequest) private

This method creates a new writer without setting any headers such as
Content-Type which should be set on every request. Make it private so
subclasses don't call it accidentally.

Change-Id: I64f9b70dadc9fe2bfbf3902ab3395b99b7d4304a

gitiles-servlet/src/main/java/com/google/gitiles/BaseServlet.java

diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/BaseServlet.java b/gitiles-servlet/src/main/java/com/google/gitiles/BaseServlet.java
index bbd432a..25285da 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/BaseServlet.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/BaseServlet.java
@@ -360,11 +360,11 @@
     setCacheHeaders(res);
   }
 
-  protected Writer newWriter(HttpServletResponse res) throws IOException {
-    return newWriter(res.getOutputStream(), res);
-  }
-
   protected static Writer newWriter(OutputStream os, HttpServletResponse res) throws IOException {
     return new OutputStreamWriter(os, res.getCharacterEncoding());
   }
+
+  private Writer newWriter(HttpServletResponse res) throws IOException {
+    return newWriter(res.getOutputStream(), res);
+  }
 }