[Download Home] Add basic tests for the DownloadManagerUi
Add tests that fire up the DownloadActivity on phones so that we can
test the DownloadManagerUi. The tests added check for:
* Selecting/deleting multiple files
* Filtering items via the sidebar
* The space display being updated.
Also changes the DownloadHistoryAdapter to ignore deleted files
when computing the amount of space used.
BUG=
616324
Committed:
https://crrev.com/6d5d67418f54ce461fc7f4abb8e823fc987f3908
Cr-Commit-Position: refs/heads/master@{#413957}