Revert "Revert "Fix NPE which occurs when MediaBrowserService.onLoadItem gives null""

Although the original CL (http://ag/1915341) is not related to the test 
failure, it was reverted. So this change makes the original CL be merged
again.

This reverts commit 6fea533c390999295d37b0debe97f88aa693d22c.

Change-Id: I10c0dea3fe45a203387ffac54d29f11e8b88ff65
4 files changed