DevTools: unflake sanity tests.

BUG=315288

TBR=vsevik

Review URL: https://codereview.chromium.org/61683003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234500 0039d316-1c4b-4281-b951-d872f2087c98
file_manager: Fix the format button

The format button was broken in two ways:

1) The button was disabled for unformatted volume, as isPathReadOnly()
   returns true for an unformatted volume, which is a reasonable behavior
   for other places (ex. disallow pasting files to an unformatted volume),
   but we should not check it here.
2) canExecute() for the format button was broken, as getCommandEntry()
   returns NULL if the event target is a button. We should use the current
   directory instead.

BUG=316526
TEST=see the steps in thebug

Review URL: https://codereview.chromium.org/66583009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234501 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234501