Add XStream to Chromium third_party.

DEPS

 # This file is used to manage the dependencies of the Chromium src repo. It is
 # used by gclient to determine what version of each dependency to check out, and
 # where.
 #
 # For more information, please refer to the official documentation:
 #   https://sites.google.com/a/chromium.org/dev/developers/how-tos/get-the-code
 #
 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 #
@@ skipping 751 matching lines @@
   {
     'name': 'objenesis',
     'pattern': '.',
     'action': ['python',
                'src/build/android/update_deps/update_third_party_deps.py',
                'download',
                '-b', 'chromium-objenesis',
                '-l', 'third_party/objenesis'
     ],
   },
+  {
+    'name': 'xstream',
+    'pattern': '.',
+    'action': ['python',
+               'src/build/android/update_deps/update_third_party_deps.py',
+               'download',
+               '-b', 'chromium-robolectric',
+               '-l', 'third_party/xstream'
+    ],
+  },
   # Downloads the VR Services and Daydream Home APKs used for VR testing on
   # Android.
   {
     'name': 'vr_services_apks',
     'pattern': '.',
     'action': ['python',
                'src/build/android/update_deps/update_third_party_deps.py',
                'download',
                '-b', 'chrome-vr-test-apks/vr_services',
                '-l', 'third_party/gvr-android-sdk/test-apks/vr_services'
@@ skipping 365 matching lines @@
 recursedeps = [
   # buildtools provides clang_format, libc++, and libc++abi
   'src/buildtools',
   # android_tools manages the NDK.
   'src/third_party/android_tools',
   # ANGLE manages DEPS that it also owns the build files for, such as dEQP.
   ("src/third_party/angle", "DEPS.chromium"),
   # SwiftShader manages DEPS that it also owns the build files for, such as Subzero.
   ("src/third_party/swiftshader", "DEPS"),
 ]