[Android WebAPK] Add build target for collecting resources to upload

This CL introduces a new build target 'prepare_webapk_shell_upload_dir'
which copies files to be uploaded to the WebAPK shell Google storage
build bucket to a single directory

BUG=969591

Change-Id: If616f8e0f55ed3a30fca7a1ec2d02b2577835d4b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1646616
Commit-Queue: Peter Kotwicz <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Reviewed-by: Yaron Friedman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#668105}
diff --git a/BUILD.gn b/BUILD.gn
index 8209523b..2adee9d2 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -299,6 +299,7 @@
       "//build/android/stacktrace:java_deobfuscate",
       "//chrome/android/webapk/shell_apk:maps_go_webapk",
       "//chrome/android/webapk/shell_apk:webapk",
+      "//chrome/android/webapk/shell_apk/prepare_upload_dir:prepare_webapk_shell_upload_dir",
       "//chrome/test/vr/perf:motopho_latency_test",
       "//components/invalidation/impl:components_invalidation_impl_junit_tests",
       "//components/journey:journey_info_fetcher",