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

chrome/browser/sync/test/integration/sync_extension_helper.cc

Index: chrome/browser/sync/test/integration/sync_extension_helper.cc
diff --git a/chrome/browser/sync/test/integration/sync_extension_helper.cc b/chrome/browser/sync/test/integration/sync_extension_helper.cc
index 467b3f5633e90b9ae9592924326fdcc5760bc39a..e4b18048b5dfdbb52025f6addafc366f4d54b4fc 100644
--- a/chrome/browser/sync/test/integration/sync_extension_helper.cc
+++ b/chrome/browser/sync/test/integration/sync_extension_helper.cc
@@ -83,7 +83,8 @@ void SyncExtensionHelper::UninstallExtension(
     Profile* profile, const std::string& name) {
   ExtensionService::UninstallExtensionHelper(
       extensions::ExtensionSystem::Get(profile)->extension_service(),
-      extensions::id_util::GenerateId(name));
+      extensions::id_util::GenerateId(name),
+      ExtensionService::kUninstallReasonSynch);
 }
 
 std::vector<std::string> SyncExtensionHelper::GetInstalledExtensionNames(