[Messages] Add flags for infrastructure and passwords infobars

This CL adds feature flags and about:flags entries for a couple of
flags:
- MessagesForAndroidInfrastructure will control initialization of
  infrastructure classes (MessageQueueManager, etc.)
- MessagesForAndroidPasswordsName will control whether save/update
  password uses Infobars or Messages UI.

BUG=1123947
[email protected]

Change-Id: I4b3e3920d2909f8e6144cc197d8fddc029356f86
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2388949
Reviewed-by: Lijin Shen <[email protected]>
Reviewed-by: Theresa  <[email protected]>
Commit-Queue: Pavel Yatsuk <[email protected]>
Cr-Commit-Position: refs/heads/master@{#804317}
diff --git a/chrome/browser/DEPS b/chrome/browser/DEPS
index 6c6d580..f50e3ce 100644
--- a/chrome/browser/DEPS
+++ b/chrome/browser/DEPS
@@ -162,6 +162,7 @@
   "+components/lookalikes/core",
   "+components/login",
   "+components/media_message_center",
+  "+components/messages/android",
   "+components/metal_util",
   "+components/metrics",
   "+components/metrics_services_manager",