Fix app_shell shutdown crash due to BrowserContextKeyedServices

apps/shell/shell_extensions_browser_client.cc

Index: apps/shell/shell_extensions_browser_client.cc
diff --git a/apps/shell/shell_extensions_browser_client.cc b/apps/shell/shell_extensions_browser_client.cc
index cc59069320a10c158c26953ce29498043c774b26..2f10c4d4610b185e410170982787eec09d89bbb8 100644
--- a/apps/shell/shell_extensions_browser_client.cc
+++ b/apps/shell/shell_extensions_browser_client.cc
@@ -5,6 +5,7 @@
 #include "apps/shell/shell_extensions_browser_client.h"
 
 #include "apps/shell/shell_app_sorting.h"
+#include "apps/shell/shell_extension_system.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/pref_service_factory.h"
 #include "base/prefs/testing_pref_store.h"
@@ -118,4 +119,15 @@ ShellExtensionsBrowserClient::GetJavaScriptDialogManager() {
   return NULL;
 }
 
+std::vector<BrowserContextKeyedServiceFactory*>
+ShellExtensionsBrowserClient::GetExtensionSystemDependencies() {
+  // No dependencies.
+  return std::vector<BrowserContextKeyedServiceFactory*>();
+}
+
+extensions::ExtensionSystem*
+ShellExtensionsBrowserClient::CreateExtensionSystem(BrowserContext* context) {
+  return new extensions::ShellExtensionSystem(context);
+}
+
 }  // namespace apps