Another CL in this topic moves libcore.net.MimeMap to package
libcore.content.type. This CL updates associated references.
Bug: 136256059
Bug: 124232146
Test: Treehugger
Test: CtsMimeMapTestCases
Exempt-From-Owner-Approval: move affecting imports only
Change-Id: I30aac8b28a1740180ea01834a2bb66b61cb255d4