Fix NPE in DisplayContent.setTouchExcludeRegion.

DisplayContent.mTapDetector is null for any non-default display. When
testing ActivityView DisplayContent.setTouchExcludeRegion() throws an
NPE when dereferencing mTapDetector.

This change adds a null test to avoid the NPE.

Fixes bug 19413700.

Change-Id: I48a66c0ed071c87b38b354eead58a4de97fb47b9
1 file changed