Fix ContentCaptureManagerTest test fail.

The test uses constructor with null parameters, but the constructor
does not allow null parameters, NPE throws then test fail. Instead
of null parameters, we pass mock objects to prevent fail.

Bug: 140955671
Test: atest FrameworksCoreTests:android.view.contentcapture.\
ContentCaptureManagerTest

Change-Id: I9dfd91da078644cd334066e07e0e5e533166c4ed