kiosk: Ensure launching latest version.

- Add a install_immediately flag to ExternalProviderImpl;
- Set install_immediately flag to true for kiosk app provider
  so that updated app install is not delayed;
- Set auto acknowledge since kiosk should not show external
  install alert;

BUG=461419

Review URL: https://codereview.chromium.org/974713002

Cr-Commit-Position: refs/heads/master@{#319005}
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 3708493..e2dc5b3 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -2108,7 +2108,8 @@
          const base::FilePath& path,
          Manifest::Location location,
          int creation_flags,
-         bool mark_acknowledged) {
+         bool mark_acknowledged,
+         bool install_immediately) {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   CHECK(crx_file::id_util::IdIsValid(id));
   if (extension_prefs_->IsExternalExtensionUninstalled(id))
@@ -2159,6 +2160,7 @@
   installer->set_expected_id(id);
   installer->set_expected_version(*version);
   installer->set_install_cause(extension_misc::INSTALL_CAUSE_EXTERNAL_FILE);
+  installer->set_install_immediately(install_immediately);
   installer->set_creation_flags(creation_flags);
 #if defined(OS_CHROMEOS)
   extensions::InstallLimiter::Get(profile_)->Add(installer, path);