Include MtpDocumentsProvider in the system image.
Include MtpDocumentsProvider in the system image.

BUG=25731385

Change-Id: I9fa90a5c4a0bca3ab7d36968b1e3b40d60d55d31

xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build