RefCounted types should not have public destructors, chrome/ remaining parts

chrome/service/cloud_print/print_system_cups.cc

Index: chrome/service/cloud_print/print_system_cups.cc
diff --git a/chrome/service/cloud_print/print_system_cups.cc b/chrome/service/cloud_print/print_system_cups.cc
index cbaf2cd91ac87d3120fa757a9cccf7cce88d596a..cb69be61493389283975545267257c55350aaf91 100644
--- a/chrome/service/cloud_print/print_system_cups.cc
+++ b/chrome/service/cloud_print/print_system_cups.cc
@@ -127,6 +127,8 @@ class PrintSystemCUPS : public PrintSystem {
   }
 
  private:
+  virtual ~PrintSystemCUPS() {}
+
   // Following functions are wrappers around corresponding CUPS functions.
   // <functions>2()  are called when print server is specified, and plain
   // version in another case. There is an issue specifing CUPS_HTTP_DEFAULT
@@ -173,9 +175,6 @@ class PrintServerWatcherCUPS
       : print_system_(print_system),
         delegate_(NULL) {
   }
-  ~PrintServerWatcherCUPS() {
-    StopWatching();
-  }
 
   // PrintSystem::PrintServerWatcher implementation.
   virtual bool StartWatching(
@@ -209,6 +208,11 @@ class PrintServerWatcherCUPS
         print_system_->GetUpdateTimeout());
   }
 
+ protected:
+  virtual ~PrintServerWatcherCUPS() {
+    StopWatching();
+  }
+
  private:
   std::string GetPrintersHash() {
     printing::PrinterList printer_list;
@@ -245,10 +249,6 @@ class PrinterWatcherCUPS
         print_system_(print_system) {
   }
 
-  ~PrinterWatcherCUPS() {
-    StopWatching();
-  }
-
   // PrintSystem::PrinterWatcher implementation.
   virtual bool StartWatching(
       PrintSystem::PrinterWatcher::Delegate* delegate) OVERRIDE{
@@ -320,6 +320,11 @@ class PrinterWatcherCUPS
         print_system_->GetUpdateTimeout());
   }
 
+ protected:
+  virtual ~PrinterWatcherCUPS() {
+    StopWatching();
+  }
+
  private:
   std::string GetSettingsHash() {
     printing::PrinterBasicInfo info;
@@ -387,6 +392,9 @@ class JobSpoolerCUPS : public PrintSystem::JobSpooler {
       delegate->OnJobSpoolFailed();
   }
 
+ protected:
+  virtual ~JobSpoolerCUPS() {}
+
  private:
   scoped_refptr<PrintSystemCUPS> print_system_;