[M114-LTS] Prevent SessionAbortedDialog dismissal via keyboard accele…

…rator

This dialog has no Cancel/Close button, but it can still
be dismissed via keyboard accelerator. This CL fixes the
exploit mentioned in the issue, but extra work might be required
to fix this behavior at dialog framework level.

(cherry picked from commit 7495fc4)

Bug: b:315761861, b:312113018
Change-Id: I15291f74f625a0759403bd73f208455e1e96d8d7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5126184
Commit-Queue: Denis Kuznetsov <[email protected]>
Auto-Submit: Denis Kuznetsov <[email protected]>
Cr-Original-Commit-Position: refs/heads/main@{#1239090}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5235001
Commit-Queue: Roger Felipe Zanoni da Silva <[email protected]>
Reviewed-by: Ahmed Fakhry <[email protected]>
Reviewed-by: Victor Gabriel Savu <[email protected]>
Owners-Override: Victor Gabriel Savu <[email protected]>
Cr-Commit-Position: refs/branch-heads/5735@{#1691}
Cr-Branched-From: 2f562e4-refs/heads/main@{#1135570}

ash/session/session_aborted_dialog.cc

@@ -67,6 +67,9 @@ SessionAbortedDialog::SessionAbortedDialog() {
                      IDS_ASH_MULTIPROFILES_SESSION_ABORT_BUTTON_LABEL));
   SetAcceptCallback(base::BindOnce(
       []() { Shell::Get()->session_controller()->RequestSignOut(); }));
+  // Prevent dismissing dialog via keyboard accelerator.
+  SetCancelCallbackWithClose(
+      base::BindRepeating([]() -> bool { return false; }));
 }
 
 SessionAbortedDialog::~SessionAbortedDialog() = default;