add tests for ResearchLogger

Bug: 6188932
Change-Id: Icf407f9d145d2b25b70d5d7bc30ee3d64561620c
diff --git a/java/proguard.flags b/java/proguard.flags
index 701786a..e33706c 100644
--- a/java/proguard.flags
+++ b/java/proguard.flags
@@ -47,6 +47,10 @@
   <init>(...);
 }
 
+-keep class com.android.inputmethod.latin.ResearchLogger {
+  void setLogFileManager(...);
+}
+
 # The support library contains references to newer platform versions.
 # Don't warn about those in case this app is linking against an older
 # platform version.  We know about them, and they are safe.