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

chrome/browser/apps/ephemeral_app_service.cc

Index: chrome/browser/apps/ephemeral_app_service.cc
diff --git a/chrome/browser/apps/ephemeral_app_service.cc b/chrome/browser/apps/ephemeral_app_service.cc
index 0832e1408eac55aa97ff88b51f3b6518c17608e1..22df68031a1749a334260ec1bdb88862928d0546 100644
--- a/chrome/browser/apps/ephemeral_app_service.cc
+++ b/chrome/browser/apps/ephemeral_app_service.cc
@@ -196,8 +196,12 @@ void EphemeralAppService::GarbageCollectApps() {
     GetAppsToRemove(app_count, app_launch_times, &remove_app_ids);
     for (std::set<std::string>::const_iterator id = remove_app_ids.begin();
          id != remove_app_ids.end(); ++id) {
-      if (service->UninstallExtension(*id, false, NULL))
+      if (service->UninstallExtension(
+              *id,
+              ExtensionService::kUninstallReasonOrphanedEphemeralExtension,
+              NULL)) {
         --app_count;
+      }
     }
   }