Add test package for MTPDocumentsProvider.

BUG=20274999

Change-Id: I179692d3b14392a0634d4c0ace21a9d96a2d0d6a
diff --git a/Android.mk b/Android.mk
index 02cd677..ec18463 100644
--- a/Android.mk
+++ b/Android.mk
@@ -2,10 +2,9 @@
 include $(CLEAR_VARS)
 
 LOCAL_MODULE_TAGS := optional
-
-LOCAL_SRC_FILES := $(call all-subdir-java-files)
-
+LOCAL_SRC_FILES := $(call all-java-files-under, src)
 LOCAL_PACKAGE_NAME := MtpDocumentsProvider
 LOCAL_CERTIFICATE := media
 
 include $(BUILD_PACKAGE)
+include $(LOCAL_PATH)/tests/Android.mk