Replace "external_install" boolean parameter with explicit enumeration in ExtensionUninstall method.

chrome/browser/ui/app_list/extension_uninstaller.cc

Index: chrome/browser/ui/app_list/extension_uninstaller.cc
diff --git a/chrome/browser/ui/app_list/extension_uninstaller.cc b/chrome/browser/ui/app_list/extension_uninstaller.cc
index 38ae50db2813ecf6cb226ee4d70a86661f32aaae..dfdad507b7c154cc5e79358037a7452c45288a65 100644
--- a/chrome/browser/ui/app_list/extension_uninstaller.cc
+++ b/chrome/browser/ui/app_list/extension_uninstaller.cc
@@ -41,9 +41,8 @@ void ExtensionUninstaller::ExtensionUninstallAccepted() {
   const extensions::Extension* extension =
       service->GetInstalledExtension(app_id_);
   if (extension) {
-    service->UninstallExtension(app_id_,
-                                false, /* external_uninstall*/
-                                NULL);
+    service->UninstallExtension(
+        app_id_, ExtensionService::kUninstallReasonUserInitiated, NULL);
   }
   controller_->OnCloseExtensionPrompt();
   CleanUp();