[ios][STG] Set InstantMessageDelegate to the messaging backend service

This CL adds InstantMessagingService and the factory for it to receive
instant messages. InstantMessagingService is empty for now.
InstantMessagingService should exist per MessagingBackendService, which
exists per profile.

This fixes the CHECK failure in crbug.com/393364013.

Bug: 393364013, 375595834
Change-Id: I3dec43ac3b20703eb8cb084e5fab3397a6cc4c32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6218570
Commit-Queue: Asami Doi <asamidoi@chromium.org>
Reviewed-by: Louis Romero <lpromero@google.com>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1417319}
NOKEYCHECK=True
GitOrigin-RevId: 07cc0ff3bc0551ab6bd2014827bd6dbb8bbf6c26
7 files changed
tree: 5f507a18c01a19faa150ddc05201ed02b08b49e4
  1. build/
  2. chrome/
  3. components/
  4. google_internal/
  5. intents/
  6. net/
  7. public/
  8. testing/
  9. third_party/
  10. tools/
  11. web/
  12. web_view/
  13. .swift-format
  14. BUILD.gn
  15. COMMON_METADATA
  16. DEPS
  17. DIR_METADATA
  18. features.gni
  19. OWNERS
  20. PRESUBMIT.py
  21. PRESUBMIT_test.py
  22. README.md
README.md

This directory holds code related to Chrome for iOS. See this document for a description of the structure underneath this directory.