Specify the version for Robolectric version

The previous default version was 3.1.1, so specifying all existing
projects to that. Please migrate to new version (3.4.2 as of today)
at your convenience.

See robolectric.org/migrating for instructions on migrating.

Test: m RunFrameworksServicesRoboTests RunCarMessengerRoboTests \
        RunStorageManagerRoboTests RunCarSettingsRoboTests \
        RunEmergencyInfoRoboTests RunManagedProvisioningRoboTests \
        RunTurboRoboTests RunStorageManagerGoogleRoboTests \
        RunBluetoothRoboTests

Change-Id: I1d53fc75f4d6b79efe4dd04c48e5d52c31a748ec
diff --git a/tests/robolectric/Android.mk b/tests/robolectric/Android.mk
index 9d48705..f9c6bf2 100644
--- a/tests/robolectric/Android.mk
+++ b/tests/robolectric/Android.mk
@@ -19,7 +19,7 @@
 
 LOCAL_JAVA_LIBRARIES := \
     junit \
-    platform-robolectric-prebuilt \
+    platform-robolectric-3.1.1-prebuilt \
     sdk_vcurrent
 
 LOCAL_STATIC_JAVA_LIBRARIES := \
@@ -51,4 +51,4 @@
 
 LOCAL_INSTRUMENT_SOURCE_DIRS := $(dir $(LOCAL_PATH))../src
 
-include prebuilts/misc/common/robolectric/run_robotests.mk
+include prebuilts/misc/common/robolectric/3.1.1/run_robotests.mk