Improve DexFile debugging

Bug: 18105751
Change-Id: I16461b61cb7723ca1f3a52080c377d013d76675b
diff --git a/dalvik/src/main/java/dalvik/system/DexFile.java b/dalvik/src/main/java/dalvik/system/DexFile.java
index 7aeba87..86bb531 100644
--- a/dalvik/src/main/java/dalvik/system/DexFile.java
+++ b/dalvik/src/main/java/dalvik/system/DexFile.java
@@ -80,7 +80,7 @@
         mCookie = openDexFile(fileName, null, 0);
         mFileName = fileName;
         guard.open("close");
-        //System.out.println("DEX FILE cookie is " + mCookie);
+        //System.out.println("DEX FILE cookie is " + mCookie + " fileName=" + fileName);
     }
 
     /**
@@ -111,7 +111,7 @@
         mCookie = openDexFile(sourceName, outputName, flags);
         mFileName = sourceName;
         guard.open("close");
-        //System.out.println("DEX FILE cookie is " + mCookie);
+        //System.out.println("DEX FILE cookie is " + mCookie + " sourceName=" + sourceName + " outputName=" + outputName);
     }
 
     /**
@@ -160,6 +160,10 @@
         return mFileName;
     }
 
+    @Override public String toString() {
+        return getName();
+    }
+
     /**
      * Closes the DEX file.
      * <p>