Revert "GetCapabilities#CheckOne: Return json content type"

This reverts commit 3841949d59dca606e18e1db2db52a116f4e283f1. It added
the )]}' XSRF protection to the beginning of the response, which may
break some users.

If trying this change again, we should include more information about
the rationale and produce a json object instead of a string so it's
easier to add new fields later.

Change-Id: I5d9fe7a7d2ccd952efc6b6f8aa062f1c6ad9a051
diff --git a/Documentation/rest-api-accounts.txt b/Documentation/rest-api-accounts.txt
index 6cb6e24..95dd4f2 100644
--- a/Documentation/rest-api-accounts.txt
+++ b/Documentation/rest-api-accounts.txt
@@ -1089,10 +1089,7 @@
 .Response
 ----
   HTTP/1.1 200 OK
-  Content-Disposition: attachment
-  Content-Type: application/json; charset=UTF-8
 
-  )]}'
   ok
 ----
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/account/GetCapabilities.java b/gerrit-server/src/main/java/com/google/gerrit/server/account/GetCapabilities.java
index 0232bf02..4058a16 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/account/GetCapabilities.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/account/GetCapabilities.java
@@ -24,7 +24,7 @@
 import com.google.gerrit.extensions.config.CapabilityDefinition;
 import com.google.gerrit.extensions.registration.DynamicMap;
 import com.google.gerrit.extensions.restapi.AuthException;
-import com.google.gerrit.extensions.restapi.Response;
+import com.google.gerrit.extensions.restapi.BinaryResult;
 import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.OptionUtil;
@@ -157,8 +157,8 @@
   @Singleton
   static class CheckOne implements RestReadView<AccountResource.Capability> {
     @Override
-    public Response<String> apply(Capability resource) {
-      return Response.ok("ok");
+    public BinaryResult apply(Capability resource) {
+      return BinaryResult.create("ok\n");
     }
   }
 }