[USS] Show USS counters in about:sync page

components/sync/driver/sync_service.h

Index: components/sync/driver/sync_service.h
diff --git a/components/sync/driver/sync_service.h b/components/sync/driver/sync_service.h
index ac37926c4912e231acd2ac2ec9df396cf6741c96..44dd4cdbe7d6080f7bb14df4208e94e4bc39318d 100644
--- a/components/sync/driver/sync_service.h
+++ b/components/sync/driver/sync_service.h
@@ -299,7 +299,7 @@ class SyncService : public DataTypeEncryptionHandler {
   // This function is used by about_sync_util.cc to help populate the about:sync
   // page.  It returns a ListValue rather than a DictionaryValue in part to make
   // it easier to iterate over its elements when constructing that page.
-  virtual base::Value* GetTypeStatusMap() const = 0;
+  virtual base::Value* GetTypeStatusMap() = 0;
 
   virtual const GURL& sync_service_url() const = 0;