Convert //extensions/browser from scoped_ptr to std::unique_ptr

extensions/browser/extension_prefs_factory.cc

Index: extensions/browser/extension_prefs_factory.cc
diff --git a/extensions/browser/extension_prefs_factory.cc b/extensions/browser/extension_prefs_factory.cc
index 888d9bd4f9f79d87e0b735a970f17c2a24a9f72c..1c1df4de49ba462303f8a1aeb7046ecc5416022e 100644
--- a/extensions/browser/extension_prefs_factory.cc
+++ b/extensions/browser/extension_prefs_factory.cc
@@ -32,7 +32,7 @@ ExtensionPrefsFactory* ExtensionPrefsFactory::GetInstance() {
 
 void ExtensionPrefsFactory::SetInstanceForTesting(
     content::BrowserContext* context,
-    scoped_ptr<ExtensionPrefs> prefs) {
+    std::unique_ptr<ExtensionPrefs> prefs) {
   Disassociate(context);
   Associate(context, std::move(prefs));
 }