Add onChange event to preference extension APIs.

chrome/browser/extensions/extension_service.cc

Index: chrome/browser/extensions/extension_service.cc
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 702fc8683b33d113257efb56d231d19947bcbb65..aa69782d555d6b528ab55f06eb24f2854d50e29e 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -34,6 +34,7 @@
 #include "chrome/browser/extensions/extension_history_api.h"
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/extensions/extension_management_api.h"
+#include "chrome/browser/extensions/extension_preference_api.h"
 #include "chrome/browser/extensions/extension_process_manager.h"
 #include "chrome/browser/extensions/extension_processes_api.h"
 #include "chrome/browser/extensions/extension_special_storage_policy.h"
@@ -452,6 +453,7 @@ void ExtensionService::InitEventRouters() {
   ExtensionAccessibilityEventRouter::GetInstance()->ObserveProfile(profile_);
   browser_event_router_.reset(new ExtensionBrowserEventRouter(profile_));
   browser_event_router_->Init();
+  preference_event_router_.reset(new ExtensionPreferenceEventRouter(profile_));
   ExtensionBookmarkEventRouter::GetInstance()->Observe(
       profile_->GetBookmarkModel());
   ExtensionCookiesEventRouter::GetInstance()->Init();
@@ -1095,6 +1097,7 @@ void ExtensionService::DestroyingProfile() {
     updater_->Stop();
   }
   browser_event_router_.reset();
+  preference_event_router_.reset();
   pref_change_registrar_.RemoveAll();
   profile_ = NULL;
   toolbar_model_.DestroyingProfile();