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

chrome/browser/apps/drive/drive_app_provider.cc

Index: chrome/browser/apps/drive/drive_app_provider.cc
diff --git a/chrome/browser/apps/drive/drive_app_provider.cc b/chrome/browser/apps/drive/drive_app_provider.cc
index 2bde9fe6bafb0eb97ba67f3d422cdcf8e9306743..3aeb5a03e001a0834f533c2d5bff442918aa1234 100644
--- a/chrome/browser/apps/drive/drive_app_provider.cc
+++ b/chrome/browser/apps/drive/drive_app_provider.cc
@@ -82,7 +82,9 @@ void DriveAppProvider::UpdateMappingAndExtensionSystem(
   if (existing_app && is_existing_app_generated) {
     extensions::ExtensionSystem::Get(profile_)
         ->extension_service()
-        ->UninstallExtension(existing_chrome_app_id, false, NULL);
+        ->UninstallExtension(existing_chrome_app_id,
+                             ExtensionService::UNINSTALL_REASON_SYNC,
+                             NULL);
   }
 }
 
@@ -191,7 +193,8 @@ void DriveAppProvider::ProcessRemovedDriveApp(const std::string& drive_app_id) {
 
   extensions::ExtensionSystem::Get(profile_)
       ->extension_service()
-      ->UninstallExtension(chrome_app_id, false, NULL);
+      ->UninstallExtension(
+          chrome_app_id, ExtensionService::UNINSTALL_REASON_SYNC, NULL);
 }
 
 void DriveAppProvider::OnDriveAppRegistryUpdated() {