[Android] Fix some nits in DownloadItemWrapper

chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java

Index: chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java b/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java
index 5c464523cf59ea0db5c90064c6f48298ee2a08d2..26e14ae7533591fb0173abaf408021fbdcc859f5 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java
@@ -30,7 +30,7 @@ import java.util.Locale;
 abstract class DownloadHistoryItemWrapper implements TimedItem {
     private static final String TAG = "download_ui";
 
-    private Long mStableId = null;
+    private Long mStableId;
 
     @Override
     public long getStableId() {
@@ -39,7 +39,7 @@ abstract class DownloadHistoryItemWrapper implements TimedItem {
             mStableId = (long) getId().hashCode();
             mStableId = (mStableId << 32) + (getTimestamp() & 0x0FFFFFFFF);
         }
-        return mStableId.longValue();
+        return mStableId;
     }
 
     /** @return Item that is being wrapped. */