Adding the --load-component-extension flag.

chrome/browser/extensions/extension_file_browser_private_api.cc

Index: chrome/browser/extensions/extension_file_browser_private_api.cc
diff --git a/chrome/browser/extensions/extension_file_browser_private_api.cc b/chrome/browser/extensions/extension_file_browser_private_api.cc
index db22b12303f6317082dc547f256bf4737d1cbc88..aecbefd94ecc7313839a64aa151c2fae534c0a7d 100644
--- a/chrome/browser/extensions/extension_file_browser_private_api.cc
+++ b/chrome/browser/extensions/extension_file_browser_private_api.cc
@@ -375,11 +375,11 @@ class RequestLocalFileSystemFunction::LocalFileSystemCallbackDispatcher
 
     // Make sure that only component extension can access the entire
     // local file system.
-    if (extension_->location() != Extension::COMPONENT
-#ifndef NDEBUG
-      && !CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kExposePrivateExtensionApi)
-#endif
+    if (extension_->location() != Extension::COMPONENT &&
+        !(extension_->location() == Extension::LOAD &&
+          CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kExposePrivateExtensionApi)
+         )
         ) {
       NOTREACHED() << "Private method access by non-component extension "
                    << extension_->id();