change ResearchLoggerTests to check file

multi-project commit with I587003f2

Bug: 6188932
Change-Id: I3d3f0c9d011301489473dc330338ea4a7ba61e9e
diff --git a/java/proguard.flags b/java/proguard.flags
index 44f8581..6cc3342 100644
--- a/java/proguard.flags
+++ b/java/proguard.flags
@@ -38,6 +38,12 @@
 
 -keep class com.android.inputmethod.latin.ResearchLogger {
   void setLogFileManager(...);
+  void clearAll();
+  com.android.inputmethod.latin.ResearchLogger$LogFileManager getLogFileManager();
+}
+
+-keep class com.android.inputmethod.latin.ResearchLogger$LogFileManager {
+  java.lang.String getContents();
 }
 
 -keep class com.android.inputmethod.keyboard.KeyboardLayoutSet$Builder {