Files.app: Make delete button on the toolbar standard button instead of CommandButton.
The period "Delete button should be shown" is not exactly same as "Delete command can be executed."
For example: While a confirm dialog overlays Files.app, the dialog consumes all input event so the delete command cannot be executed, but still the delete button should be shown under the overlaying dialog.
BUG=459402,457113
TEST=manually checked the repro steps on each issue.
Review URL: https://codereview.chromium.org/951443002
Cr-Commit-Position: refs/heads/master@{#317569}
5 files changed
