The admin of a manged device can take a number actions that will be
listed in the "Changes made by your organization's admin" section of
Settings. If the admin has not taken any such actions, the section
will be empty and should be hidden. This is accomplished by having a
PreferenceController for the section that observes the state of the
PreferenceControllers inside it.
Bug: 35912953
Test: m RunSettingsRoboTests
Merged-in: Ia95754493ee6c5a19b4aa9731fd56fd558e61849
Change-Id: I82ca00b757001390f9a517b0c07057bdc49dab20
493495452a