Becky Siegel 70a8269b52 Add diff preferences to change view
Noteworthy decisions:
- Preferences are hidden when diff prefs are not loaded or the user is not
logged in.
- Preferences are hidden on small screens
- The trigger button is in gr-change-view but the gr-diff-preferences
  is part of gr-file-list. This is because gr-file-list because diff
  preferences and local preferences are more closely tied with that
  than the change view. In order to put it in the change view, local
  prefs would also have to be two-way bound back.

Also fixes computePrefsButtonHidden in gr-diff-view as well. The
function did not work as intended before. If preferences didn't exist,
the function would not get called, and the container would not be
hidden.

Bug: Issue 5426
Change-Id: I361cdf132c6e15b5ae2f15e62af318cfa05161ce
2017-05-10 15:55:57 -07:00
..