[Extensions] Make chrome://extensions use developerPrivate for unpacked loading

chrome/browser/extensions/unpacked_installer.h

Index: chrome/browser/extensions/unpacked_installer.h
diff --git a/chrome/browser/extensions/unpacked_installer.h b/chrome/browser/extensions/unpacked_installer.h
index 853cc3979df9b7164909f0597f2bd95442db1e33..db95a07d89e8cf0b8ec1c81c86231a00ff151550 100644
--- a/chrome/browser/extensions/unpacked_installer.h
+++ b/chrome/browser/extensions/unpacked_installer.h
@@ -29,8 +29,9 @@ class Extension;
 class UnpackedInstaller
     : public base::RefCountedThreadSafe<UnpackedInstaller> {
  public:
-  typedef base::Callback<void(const base::FilePath&, const std::string&)>
-      OnFailureCallback;
+  using CompletionCallback = base::Callback<void(const Extension* extension,
+                                                 const base::FilePath&,
+                                                 const std::string&)>;
 
   static scoped_refptr<UnpackedInstaller> Create(
       ExtensionService* extension_service);
@@ -68,6 +69,10 @@ class UnpackedInstaller
     be_noisy_on_failure_ = be_noisy_on_failure;
   }
 
+  void set_completion_callback(const CompletionCallback& callback) {
+    callback_ = callback;
+  }
+
  private:
   friend class base::RefCountedThreadSafe<UnpackedInstaller>;
 
@@ -133,6 +138,8 @@ class UnpackedInstaller
   // installed.
   ExtensionInstallChecker install_checker_;
 
+  CompletionCallback callback_;
+
   DISALLOW_COPY_AND_ASSIGN(UnpackedInstaller);
 };