Fix the last remaining @deprecated tag without comment warning.

Change-Id: Id4c50dee743fa781ca3f470f97ed76d1501f7222
diff --git a/core/java/android/webkit/CacheManager.java b/core/java/android/webkit/CacheManager.java
index d5058b0..d171990 100644
--- a/core/java/android/webkit/CacheManager.java
+++ b/core/java/android/webkit/CacheManager.java
@@ -284,7 +284,7 @@
     // only called from WebCore Thread
     // make sure to call startCacheTransaction/endCacheTransaction in pair
     /**
-     * @deprecated
+     * @deprecated Always returns false.
      */
     @Deprecated
     public static boolean startCacheTransaction() {
@@ -294,7 +294,7 @@
     // only called from WebCore Thread
     // make sure to call startCacheTransaction/endCacheTransaction in pair
     /**
-     * @deprecated
+     * @deprecated Always returns false.
      */
     @Deprecated
     public static boolean endCacheTransaction() {