Fix the crash when applying daily wallpaper without network connection

It's because CustomizationPickerActivity is cast to BaseActivity to call isSafeToCommitFragmentTransaction(), but it is not a BaseActivity.
Extract isSafeToCommitFragmentTransaction() to an interface to let CustomizationPickerActivity to implement it.

Bug: 167943713
Change-Id: I497620f86f5309392761ce11e19bc183a70178cb
3 files changed