Add new mirror for AppRTC due to code move at GitHub.

DEPS

 # DEPS file that pulls down dependencies that are needed to build and
 # execute WebRTC specific tests from a Chromium checkout.
 
 vars = {
   'git_url':
      'https://chromium.googlesource.com'
 }
 
 deps = {
-  'webrtc-samples':
-    Var('git_url') + '/external/webrtc-samples.git',
+  # TODO(kjellander): Replace the AppRTC location with a GoB mirror as soon as
+  # crbug.com/455758 is resolved.
+  'apprtc':
+    'https://github.com/webrtc/apprtc.git',
   'webrtc.DEPS/third_party/manifestdestiny':
     Var('git_url') + '/chromium/deps/manifestdestiny.git@46ae53ac463e23bfefec374a81806355ea598ac4',
   'webrtc.DEPS/third_party/mozdownload':
     Var('git_url') + '/chromium/deps/mozdownload.git@dcb2344c8f16caae7762c4557d08f2eca536a40a',
   'webrtc.DEPS/third_party/mozinfo':
     Var('git_url') + '/chromium/deps/mozinfo.git@f4cc257e21c48bc33dc1d12123d934a4dcaa120c',
   'webrtc.DEPS/third_party/mozprocess':
     Var('git_url') + '/chromium/deps/mozprocess.git@11d11bebc8517dcedec71f377cbec07fb91a3b1f',
   'webrtc.DEPS/third_party/mozprofile':
     Var('git_url') + '/chromium/deps/mozprofile.git@313295a0d9e1687dafa58e12f1f01b093a136446',
@@ skipping 33 matching lines @@
     "action" : ["python",
                 "webrtc.DEPS/build_mercurial_local.py"],
   },
   {
     # Build AppRTC Collider using the golang toolchain.
     "pattern": ".",
     "action" : ["python",
                 "webrtc.DEPS/build_apprtc_collider.py"],
   },
   {
-    # Build AppRTC closure Javascript.
+    # Build the AppRTC App Engine Application.
     "pattern": ".",
     "action" : ["python",
-                "webrtc.DEPS/build_apprtc_closure.py"],
+                "webrtc.DEPS/build_apprtc_appengine_app.py"],
   },
   {
     # Download media files and tools used by the webrtc quality browser tests,
     # chrome/browser/media/chrome_webrtc_audio_quality_browsertest.cc and
     # chrome/browser/media/chrome_webrtc_video_quality_browsertest.cc.
     "pattern": "\\.sha1",
     "action": ["download_from_google_storage",
                "--directory",
                "--num_threads=10",
                "--bucket", "chromium-webrtc-resources",
@@ skipping 12 matching lines @@
   {
     # Download firefox for the Firefox AppRTC test.
     "pattern": ".",
     "action" : ["python",
                 "webrtc.DEPS/download_firefox_nightly.py",
                 "--clean-old-firefox-archives",
                 "--target-dir",
                 "firefox-nightly"],
   },
 ]