Roll LevelDB to r31.

DEPS

 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",
   "webkit_trunk": "http://svn.webkit.org/repository/webkit/trunk",
   "nacl_trunk": "http://src.chromium.org/native_client/trunk",
   "webkit_revision": "88220",
   "chromium_git": "http://git.chromium.org/git",
   "swig_revision": "69281",
   # These hashes need to be updated when nacl_revision is changed.
@@ skipping 51 matching lines @@
     "/trunk/deps/third_party/hunspell_dictionaries@79099",
 
   "src/third_party/safe_browsing/testing":
     (Var("googlecode_url") % "google-safe-browsing") + "/trunk/testing@106",
 
   "src/third_party/cacheinvalidation/files/src/google":
     (Var("googlecode_url") % "google-cache-invalidation-api") +
     "/trunk/src/google@80",
 
   "src/third_party/leveldb":
-    (Var("googlecode_url") % "leveldb") + "/trunk@30",
+    (Var("googlecode_url") % "leveldb") + "/trunk@31",
 
   "src/third_party/snappy/src":
     (Var("googlecode_url") % "snappy") + "/trunk@37",
 
   "src/tools/gyp":
     (Var("googlecode_url") % "gyp") + "/trunk@931",
 
   "src/v8":
     (Var("googlecode_url") % "v8") + "/trunk@" + Var("v8_revision"),
 
@@ skipping 280 matching lines @@
   {
     # This downloads binaries for Native Client's integrated runtime (IRT)
     # library, which is built as NaCl untrusted code.
     "pattern": ".",
     "action": ["python", "src/build/download_nacl_irt.py",
                "--nacl_revision", Var("nacl_revision"),
                "--file_hash", "x86_32", Var("nacl_irt_hash_x86_32"),
                "--file_hash", "x86_64", Var("nacl_irt_hash_x86_64")],
   },
 ]