Arc: Call callback in OnRequestTextSelectionActions when result is empty

This CL lets OnRequestTextSelectionActions() call `callback` even when
text selection actions result is empty.
By using std::vector::data, it won't crash even when actions is empty.

(cherry picked from commit 8e12616)

Bug: 1406041
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4159743
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Alan Zhao <ayzhao@google.com>
Commit-Queue: Alan Zhao <ayzhao@google.com>
Cr-Original-Commit-Position: refs/heads/main@{#1092499}
Change-Id: I4d86fabe6967ac7c6776c6277ec75d365c602953
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4165882
Reviewed-by: David Jacobo <djacobo@chromium.org>
Cr-Commit-Position: refs/branch-heads/5481@{#297}
Cr-Branched-From: 130f3e4-refs/heads/main@{#1084008}

chrome/browser/ash/arc/intent_helper/arc_intent_helper_mojo_ash.cc

@@ -123,7 +123,7 @@ void ArcIntentHelperMojoAsh::OnRequestTextSelectionActions(
     std::vector<mojom::TextSelectionActionPtr> actions) {
   size_t actions_count = actions.size();
   auto converted_actions = std::vector<TextSelectionAction*>(actions_count);
-  TextSelectionAction** converted_actions_ptr = &converted_actions[0];
+  TextSelectionAction** converted_actions_ptr = converted_actions.data();
   base::RepeatingClosure barrier_closure = base::BarrierClosure(
       actions_count, base::BindOnce(
                          [](std::vector<TextSelectionAction*> actions,