Move app_shell specific impl from athena_lib to athena_shell_lib

athena/test/sample_activity_factory.cc

Index: athena/test/sample_activity_factory.cc
diff --git a/athena/test/sample_activity_factory.cc b/athena/test/sample_activity_factory.cc
index 429342a4be98b40e1c2c41d70633becbef3803d4..71ffef56d5d0610d681365257a31ef1d2039db73 100644
--- a/athena/test/sample_activity_factory.cc
+++ b/athena/test/sample_activity_factory.cc
@@ -42,5 +42,11 @@ Activity* SampleActivityFactory::CreateAppActivity(
       kDefaultAppColor, kDefaultAppContentColor, base::UTF8ToUTF16("App"));
 }
 
+Activity* SampleActivityFactory::CreateAppActivity(
+    apps::AppWindow* app_window) {
+  return new SampleActivity(
+      kDefaultAppColor, kDefaultAppContentColor, base::UTF8ToUTF16("App"));
+}
+
 }  // namespace test
 }  // namespace athena