Delete DexFile closeguard

Since class unloading deletes class loaders, it can cause CloseGuard
warnings for the dex files in the dex path list. The parent finalizer
can not call close() since the finalizer ordering is not specified.

Test: test-art-host

Bug: 29820420

(cherry picked from commit 97db693d0ba5ebbe78df3058f5ce2133a6511d18)

Change-Id: I3d5bb133aa2ae537fb1731f99dbd1723811260c2
diff --git a/dalvik/src/main/java/dalvik/system/DexFile.java b/dalvik/src/main/java/dalvik/system/DexFile.java
index f1ec29d..9fa2bb1 100644
--- a/dalvik/src/main/java/dalvik/system/DexFile.java
+++ b/dalvik/src/main/java/dalvik/system/DexFile.java
@@ -41,7 +41,6 @@
     private Object mCookie;
     private Object mInternalCookie;
     private final String mFileName;
-    private final CloseGuard guard = CloseGuard.get();
 
     /**
      * Opens a DEX file from a given File object. This will usually be a ZIP/JAR
@@ -113,7 +112,6 @@
         mCookie = openDexFile(fileName, null, 0, loader, elements);
         mInternalCookie = mCookie;
         mFileName = fileName;
-        guard.open("close");
         //System.out.println("DEX FILE cookie is " + mCookie + " fileName=" + fileName);
     }
 
@@ -250,7 +248,6 @@
             if (closeDexFile(mInternalCookie)) {
                 mInternalCookie = null;
             }
-            guard.close();
             mCookie = null;
         }
     }
@@ -349,9 +346,6 @@
      */
     @Override protected void finalize() throws Throwable {
         try {
-            if (guard != null) {
-                guard.warnIfOpen();
-            }
             if (mInternalCookie != null && !closeDexFile(mInternalCookie)) {
                 throw new AssertionError("Failed to close dex file in finalizer.");
             }