GitLab

Add ability to run integration tests with MyFilesVolume feature
enabled.

Change Files app base BrowserTest class to:

1. create folder Downloads when the flag MyFilesVolume is enabled, so
it emulates the same condition that happens in the device.

2. |DownloadsTestVolume.CreateEntry| method to prefix entries with
"Downloads" so they are all created inside the sub-folder downloads.
This is needed to make the test logic compatible with the flag
MyFilesVolume enabled or disabled. Since MyFiles becomes the root
volume when it's enabled, entries would be created in MyFiles. This
should be cleaned up once MyFilesVolume is fully rolled out.

MyFiles/FilesAppBrowserTest.Test/myFilesUpdatesChildren_MyFilesVolume

Test: --gtest_filter="
Bug: 873539
Change-Id: I1464b7fa6f30f16cd7ddaa5900b11e95fafd9208
Reviewed-on: https://chromium-review.googlesource.com/c/1334989Reviewed-by: Sam McNally <sammc@chromium.org>
Commit-Queue: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608251}