Rolled cache invalidation library to @21 to fix windows warnings.

DEPS

 vars = {
   "webkit_trunk":
   "http://svn.webkit.org/repository/webkit/trunk",
   "webkit_revision": "61334",
   "ffmpeg_revision": "49485",
   "skia_revision": "576",
   "chromium_git": "http://src.chromium.org/git",
   "swig_revision": "40423",
   "nacl_revision": "2441",
   "libvpx_revision": "47941",
@@ skipping 28 matching lines @@
   "src/third_party/hunspell":
    "/trunk/deps/third_party/hunspell128@48011",
 
   "src/third_party/hunspell_dictionaries":
    "/trunk/deps/third_party/hunspell_dictionaries@48011",
 
   "src/third_party/protobuf2/src":
     "http://protobuf.googlecode.com/svn/trunk@327",
 
   "src/third_party/cacheinvalidation/files":
-    "http://google-cache-invalidation-api.googlecode.com/svn/trunk@13",
+    "http://google-cache-invalidation-api.googlecode.com/svn/trunk@21",
 
   "src/tools/gyp":
     "http://gyp.googlecode.com/svn/trunk@826",
 
   "src/v8":
     "http://v8.googlecode.com/svn/trunk@4875",
 
   "src/native_client":
     "http://nativeclient.googlecode.com/svn/trunk/src/native_client@" +
     Var("nacl_revision"),
@@ skipping 226 matching lines @@
   },
   {
     # Workaround XCode dependecies problem.
     # TODO(bradnelson): remove this when fixed.
     "pattern": ".",
     "action": ["python",
                "src/build/mac/clobber_generated_headers.py"],
   },
 ]