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

chrome/browser/extensions/extension_sync_service.cc

Index: chrome/browser/extensions/extension_sync_service.cc
diff --git a/chrome/browser/extensions/extension_sync_service.cc b/chrome/browser/extensions/extension_sync_service.cc
index b125e728df6b034b8d1b6bdcfeb33066eca3e16e..e1b1af255e5dff72fecab9ba397e0ab9e31bd38f 100644
--- a/chrome/browser/extensions/extension_sync_service.cc
+++ b/chrome/browser/extensions/extension_sync_service.cc
@@ -449,7 +449,8 @@ bool ExtensionSyncService::ProcessExtensionSyncDataHelper(
 
   // Handle uninstalls first.
   if (extension_sync_data.uninstalled()) {
-    if (!extension_service_->UninstallExtensionHelper(extension_service_, id)) {
+    if (!extension_service_->UninstallExtensionHelper(
+            extension_service_, id, ExtensionService::UNINSTALL_REASON_SYNC)) {
       LOG(WARNING) << "Could not uninstall extension " << id
                    << " for sync";
     }