Revert 51330 - Updated cache-invalidation library to @25.

BUG=34647
TEST=sync_listen_notifications

Review URL: http://codereview.chromium.org/2880008

TBR=akalin@chromium.org
Review URL: http://codereview.chromium.org/2866037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@51332 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -46,7 +46,7 @@ deps = {
     "http://protobuf.googlecode.com/svn/trunk@327",
 
   "src/third_party/cacheinvalidation/files":
-    "http://google-cache-invalidation-api.googlecode.com/svn/trunk@25",
+    "http://google-cache-invalidation-api.googlecode.com/svn/trunk@21",
 
   "src/tools/gyp":
     "http://gyp.googlecode.com/svn/trunk@826",