GitLab

To support testing, adds ProgressCenter function to inhibit file
operation completed messages being propagated to progress center panels.

Test copies a file, remembers the text written on the progress panel,
closes the foreground window, then opens a new foreground window and
verifies that a progress panel is created with the same text as the
original window.

Bug: 988137
Tests: --gtest_filter="*FilesAppBrowserTest.Test/transferInfoIsRemembered"
Change-Id: If48d4ba1c181bc615a6e71abfd3814d2ec239d83
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1898902
Commit-Queue: Alex Danilo <adanilo@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712821}