Add accessibility-developer-tools to DEPS (with full SHA-1).

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://%(repo)s.svn.sourceforge.net/svnroot/%(repo)s",
   "webkit_trunk": "http://svn.webkit.org/repository/webkit/trunk",
   "nacl_trunk": "http://src.chromium.org/native_client/trunk",
@@ skipping 297 matching lines @@
     "/trunk/tools/deps2git@163971",
 
   "src/third_party/webpagereplay":
     (Var("googlecode_url") % "web-page-replay") + "/trunk@501",
 
   "src/third_party/pywebsocket/src":
     (Var("googlecode_url") % "pywebsocket") + "/trunk/src@662",
 
   "src/third_party/opus/src":
     "/trunk/deps/third_party/opus@165487",
+
+  "src/third_party/accessibility-developer-tools":
+    Var("chromium_git") + "/external/accessibility-developer-tools.git@c77344d0d39b2365775b8e1d86bafcd5ac407444",
 }
 
 
 deps_os = {
   "win": {
     "src/chrome/tools/test/reference_build/chrome_win":
       "/trunk/deps/reference_builds/chrome_win@137747",
 
     "src/third_party/cygwin":
       "/trunk/deps/third_party/cygwin@133786",
@@ skipping 301 matching lines @@
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
   {
     # Check for landmines (reasons to clobber the build).
     "pattern": ".",
     "action": ["python", "src/build/landmines.py"],
   },
 ]