Convert ProtocolHandlerRegistry to be a ProfileKeyedService.

chrome/browser/profiles/profile_dependency_manager.cc

Index: chrome/browser/profiles/profile_dependency_manager.cc
diff --git a/chrome/browser/profiles/profile_dependency_manager.cc b/chrome/browser/profiles/profile_dependency_manager.cc
index 05cbcc47e6035e0369edfcbcf3838c95a510ca55..1c2a856a1dba9c51f13b4ff7e82df39698d41fe8 100644
--- a/chrome/browser/profiles/profile_dependency_manager.cc
+++ b/chrome/browser/profiles/profile_dependency_manager.cc
@@ -13,6 +13,7 @@
 #include "chrome/browser/bookmarks/bookmark_model_factory.h"
 #include "chrome/browser/captive_portal/captive_portal_service_factory.h"
 #include "chrome/browser/content_settings/cookie_settings.h"
+#include "chrome/browser/custom_handlers/protocol_handler_registry_factory.h"
 #include "chrome/browser/download/download_service_factory.h"
 #include "chrome/browser/extensions/api/commands/command_service_factory.h"
 #include "chrome/browser/extensions/api/discovery/suggested_links_registry_factory.h"
@@ -235,6 +236,7 @@ void ProfileDependencyManager::AssertFactoriesBuilt() {
   prerender::PrerenderManagerFactory::GetInstance();
   prerender::PrerenderLinkManagerFactory::GetInstance();
   ProfileSyncServiceFactory::GetInstance();
+  ProtocolHandlerRegistryFactory::GetInstance();
 #if defined(ENABLE_PROTECTOR_SERVICE)
   protector::ProtectorServiceFactory::GetInstance();
 #endif