Convert ProtocolHandlerRegistry to be a ProfileKeyedService.

chrome/browser/custom_handlers/protocol_handler_registry.h

Index: chrome/browser/custom_handlers/protocol_handler_registry.h
diff --git a/chrome/browser/custom_handlers/protocol_handler_registry.h b/chrome/browser/custom_handlers/protocol_handler_registry.h
index 18f01111eedac6b82a6b48dee98f77de9c5fbccb..2110bb4e93fc58fdc1cea5bd469b1c7bbe6e5ea0 100644
--- a/chrome/browser/custom_handlers/protocol_handler_registry.h
+++ b/chrome/browser/custom_handlers/protocol_handler_registry.h
@@ -11,7 +11,6 @@
 #include <vector>
 
 #include "base/basictypes.h"
-#include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "base/values.h"
 #include "chrome/browser/profiles/profile.h"
@@ -28,9 +27,8 @@
 // Profile::InitRegisteredProtocolHandlers(), and they should be the only
 // instances of this class.
 
-class ProtocolHandlerRegistry
-    : public base::RefCountedThreadSafe<
-          ProtocolHandlerRegistry, content::BrowserThread::DeleteOnIOThread> {
+class ProtocolHandlerRegistry : public ProfileKeyedService {
+
  public:
   class DefaultClientObserver
       : public ShellIntegration::DefaultWebClientObserver {
@@ -117,6 +115,9 @@ class ProtocolHandlerRegistry
   // Returns true if this handler is the default handler for its protocol.
   bool IsDefault(const ProtocolHandler& handler) const;
 
+  // Initializes default protocol setttings and loads them from prefs.
+  void InitProtocolSettings();
+
   // Loads a user's registered protocol handlers.
   void Load();