Adding common  code for instrumentation and robolectric tests

Change-Id: Ia338f0565868bb174ef5f6721924944792866be6
diff --git a/robolectric_tests/Android.mk b/robolectric_tests/Android.mk
index bbc62e9..3fa9b0a 100644
--- a/robolectric_tests/Android.mk
+++ b/robolectric_tests/Android.mk
@@ -22,7 +22,10 @@
 LOCAL_MODULE_CLASS := JAVA_LIBRARIES
 
 LOCAL_SDK_VERSION := system_current
-LOCAL_SRC_FILES := $(call all-java-files-under, src)
+LOCAL_SRC_FILES := \
+	$(call all-java-files-under, src) \
+	$(call all-java-files-under, ../tests/src_common)
+
 LOCAL_STATIC_JAVA_LIBRARIES := \
     androidx.test.runner \
     androidx.test.rules \