Remove some Profile-keyed factory boilerplate: management omnibox preference push_messaging.

chrome/browser/extensions/api/preference/preference_api.cc

Index: chrome/browser/extensions/api/preference/preference_api.cc
diff --git a/chrome/browser/extensions/api/preference/preference_api.cc b/chrome/browser/extensions/api/preference/preference_api.cc
index e3e8ce58441ef45c34daec2aaa0c67c9584fd70c..0b7b3b1df9afa84d84c83172cad71555a1a2d941 100644
--- a/chrome/browser/extensions/api/preference/preference_api.cc
+++ b/chrome/browser/extensions/api/preference/preference_api.cc
@@ -7,6 +7,7 @@
 #include <map>
 #include <utility>
 
+#include "base/lazy_instance.h"
 #include "base/memory/singleton.h"
 #include "base/stl_util.h"
 #include "base/stringprintf.h"
@@ -321,6 +322,14 @@ void PreferenceAPI::Shutdown() {
   ExtensionSystem::Get(profile_)->event_router()->UnregisterObserver(this);
 }
 
+static base::LazyInstance<ProfileKeyedAPIFactory<PreferenceAPI> >
+g_factory = LAZY_INSTANCE_INITIALIZER;
+
+// static
+ProfileKeyedAPIFactory<PreferenceAPI>* PreferenceAPI::GetFactoryInstance() {
+  return &g_factory.Get();
+}
+
 void PreferenceAPI::OnListenerAdded(const EventListenerInfo& details) {
   preference_event_router_.reset(new PreferenceEventRouter(profile_));
   ExtensionSystem::Get(profile_)->event_router()->UnregisterObserver(this);