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 25d5fc98c97f21e01330ed78495d90f1f18e57c4..9f015acc2d3c9f7cf68c39a552f80bb2834fe8b1 100644
--- a/chrome/browser/profiles/profile_dependency_manager.cc
+++ b/chrome/browser/profiles/profile_dependency_manager.cc
@@ -12,6 +12,7 @@
 #include "chrome/browser/background/background_contents_service_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"
@@ -213,6 +214,7 @@ void ProfileDependencyManager::AssertFactoriesBuilt() {
   predictors::PredictorDatabaseFactory::GetInstance();
   prerender::PrerenderManagerFactory::GetInstance();
   ProfileSyncServiceFactory::GetInstance();
+  ProtocolHandlerRegistryFactory::GetInstance();
 #if defined(ENABLE_PROTECTOR_SERVICE)
   protector::ProtectorServiceFactory::GetInstance();
 #endif