arc: Handle default app not availble case.

components/arc/test/fake_app_instance.cc

Index: components/arc/test/fake_app_instance.cc
diff --git a/components/arc/test/fake_app_instance.cc b/components/arc/test/fake_app_instance.cc
index 7ae00a6398e824804db1f0c135ae8ddde2904ea2..b9885a33973ca00f94075bd718f1eaacab6f92ef 100644
--- a/components/arc/test/fake_app_instance.cc
+++ b/components/arc/test/fake_app_instance.cc
@@ -191,6 +191,19 @@ void FakeAppInstance::SendPackageUninstalled(const std::string& package_name) {
   app_host_->OnPackageRemoved(package_name);
 }
 
+void FakeAppInstance::SendInstallationStarted(const std::string& package_name) {
+  app_host_->OnInstallationStarted(package_name);
+}
+
+void FakeAppInstance::SendInstallationFinished(const std::string& package_name,
+                                               bool success) {
+  mojom::InstallationResult result;
+  result.package_name = package_name;
+  result.success = success;
+  app_host_->OnInstallationFinished(
+      mojom::InstallationResultPtr(result.Clone()));
+}
+
 void FakeAppInstance::CanHandleResolution(
     const std::string& package_name,
     const std::string& activity,