Remove profile-keyed factory boilerplates.

chrome/browser/extensions/api/history/history_api.cc

Index: chrome/browser/extensions/api/history/history_api.cc
diff --git a/chrome/browser/extensions/api/history/history_api.cc b/chrome/browser/extensions/api/history/history_api.cc
index 06b5fcc4fc968291549084171d99ada8f3c6c36a..a8a0d09adbd276d51c329589aafb5a64bcea9162 100644
--- a/chrome/browser/extensions/api/history/history_api.cc
+++ b/chrome/browser/extensions/api/history/history_api.cc
@@ -8,6 +8,7 @@
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/json/json_writer.h"
+#include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/string_number_conversions.h"
@@ -212,6 +213,14 @@ void HistoryAPI::Shutdown() {
   ExtensionSystem::Get(profile_)->event_router()->UnregisterObserver(this);
 }
 
+static base::LazyInstance<ProfileKeyedAPIFactory<HistoryAPI> >
+g_factory = LAZY_INSTANCE_INITIALIZER;
+
+// static
+ProfileKeyedAPIFactory<HistoryAPI>* HistoryAPI::GetFactoryInstance() {
+  return &g_factory.Get();
+}
+
 void HistoryAPI::OnListenerAdded(const EventListenerInfo& details) {
   history_event_router_.reset(new HistoryEventRouter(profile_));
   ExtensionSystem::Get(profile_)->event_router()->UnregisterObserver(this);