Make ChildProcessHost be used through an interface in content/public, instead of by inheritence.

chrome/service/service_utility_process_host.h

Index: chrome/service/service_utility_process_host.h
===================================================================
--- chrome/service/service_utility_process_host.h	(revision 112775)
+++ chrome/service/service_utility_process_host.h	(working copy)
@@ -21,7 +21,6 @@
 #include "content/public/common/child_process_host_delegate.h"
 #include "printing/pdf_render_settings.h"
 
-class ChildProcessHost;
 class CommandLine;
 class ScopedTempDir;
 
@@ -29,6 +28,10 @@
 class MessageLoopProxy;
 }  // namespace base
 
+namespace content {
+class ChildProcessHost;
+}
+
 namespace printing {
 class Emf;
 struct PageRange;
@@ -135,7 +138,7 @@
       const printing::PrinterCapsAndDefaults& caps_and_defaults);
   void OnGetPrinterCapsAndDefaultsFailed(const std::string& printer_name);
 
-  scoped_ptr<ChildProcessHost> child_process_host_;
+  scoped_ptr<content::ChildProcessHost> child_process_host_;
   base::ProcessHandle handle_;
   // A pointer to our client interface, who will be informed of progress.
   scoped_refptr<Client> client_;