Roll third_party/webpagereplay from r520 to r521.

DEPS

 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 
 vars = {
   # Use this googlecode_url variable only if there is an internal mirror for it.
   # If you do not know, use the full path while defining your new deps entry.
   "googlecode_url": "http://%s.googlecode.com/svn",
   "sourceforge_url": "http://svn.code.sf.net/p/%(repo)s/code",
   "webkit_trunk": "http://src.chromium.org/blink/trunk",
   "nacl_trunk": "http://src.chromium.org/native_client/trunk",
@@ skipping 215 matching lines @@
      (Var("googlecode_url") % "libphonenumber") + "/trunk/cpp/test@" +
          Var("libphonenumber_revision"),
   "src/third_party/libphonenumber/src/resources":
      (Var("googlecode_url") % "libphonenumber") + "/trunk/resources@" +
          Var("libphonenumber_revision"),
 
   "src/tools/deps2git":
     "/trunk/tools/deps2git@214390",
 
   "src/third_party/webpagereplay":
-    (Var("googlecode_url") % "web-page-replay") + "/trunk@520",
+    (Var("googlecode_url") % "web-page-replay") + "/trunk@521",
 
   "src/third_party/pywebsocket/src":
     (Var("googlecode_url") % "pywebsocket") + "/trunk/src@662",
 
   "src/third_party/opus/src":
     "/trunk/deps/third_party/opus@185324",
 
   "src/third_party/accessibility-developer-tools":
     Var("chromium_git") + "/external/accessibility-developer-tools.git@2e3c9c8e49277a0ca1eeba510271eb03f9486d8f",
 
@@ skipping 372 matching lines @@
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
   {
     # Check for landmines (reasons to clobber the build).
     "name": "landmines",
     "pattern": ".",
     "action": ["python", "src/build/landmines.py"],
   },
 ]