Don't throw away wallpaper bitmap just because we are hidden.

TRIM_MEMORY_UI_HIDDEN > TRIM_MEMORY_RUNNING constants, so we only
need to throw away the wallpaper if we are actually running low on
memory.

Bug: 28769940
Change-Id: I8aa27d081bbcc2eff553e9420b2b9b0920f3781f
1 file changed