Add empty activity projects for benchmarking

empty-activity/README.google:

Name: Empty Android Activity
URL: https://github.com/christofferqa/empty_android_activity
Version: NA
Revision: 2d297ec3373dadb03cbae916b9feba4792563156
Date: Dec 16, 2021
License: Apache License 2.0


empty-compose-activity/README.google:

Name: Empty Android Compose Activity
URL: https://github.com/christofferqa/empty_android_compose_activity
Version: NA
Revision: 3c8111b8b7d6e9184049a07e2b96702d7b33d03e
Date: Dec 16, 2021
License: Apache License 2.0

Change-Id: I8228e485251da3589542f6363016ae615f2d08bc

third_party/opensource-apps/empty-activity.tar.gz.sha1

diff --git a/third_party/opensource-apps/empty-activity.tar.gz.sha1 b/third_party/opensource-apps/empty-activity.tar.gz.sha1
new file mode 100644
index 0000000..4244c67
--- /dev/null
+++ b/third_party/opensource-apps/empty-activity.tar.gz.sha1
@@ -0,0 +1 @@
+ff20836a8bc101c9ec5ded3fe025013605453919
\ No newline at end of file