Add MB configs for the GN bots on the V8 waterfalls.

tools/mb/mb_config.pyl

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   # This is the list of configs that you can pass to mb; each config
   # represents a particular combination of GYP_DEFINES/gn args that
   # we must support. A given config *may* be platform-specific but
   # is not necessarily so (i.e., we might have mac, win, and linux
   # bots all using the 'gn_release_bot' config).
@@ skipping 144 matching lines @@
       'Win x64 GN (dbg)': 'gn_debug_static_bot',
       'Win8 GN': 'gn_release_bot_x86',
       'Win8 GN (dbg)': 'gn_debug_static_bot_x86',
     },
     'chromium.webkit': {
       'Android GN': 'android_gn_release_bot',
       'Android GN (dbg)': 'android_gn_debug_bot',
       'Linux GN': 'gn_release_bot',
       'Linux GN (dbg)': 'gn_debug_bot'
     },
+    'client.v8': {
+      'V8 Linux GN': 'gn_release_bot',
+      'V8 Android GN (dbg)': 'android_gn_debug_bot',
+    },
     'tryserver.blink': {
       'android_chromium_gn_compile_rel': 'android_gn_release_bot',
       'linux_chromium_gn_rel': 'gn_release_bot',
     },
     'tryserver.chromium.linux': {
       'android_chromium_gn_compile_dbg': 'android_gn_debug_bot',
       'android_chromium_gn_compile_rel': 'android_gn_release_trybot',
       'linux_chromium_gn_chromeos_rel': 'chromeos_gn_release_trybot',
       'linux_chromium_gn_chromeos_dbg': 'chromeos_gn_debug_bot',
       'linux_chromium_gn_dbg': 'gn_debug_bot', 
       'linux_chromium_gn_rel': 'gn_release_trybot', 
       'linux_chromium_gn_upload_x64': 'gn_release_bot',
       'linux_chromium_gn_upload_x86': 'gn_release_bot_x86',
     },
     'tryserver.chromium.mac': {
       'mac_chromium_gn_dbg': 'gn_debug_static_bot',
       'mac_chromium_gn_rel': 'gn_release_trybot',
       'mac_chromium_gn_upload': 'gn_release_bot',
     },
     'tryserver.chromium.win': {
       'win_chromium_gn_x64_dbg': 'gn_debug_static_bot',
       'win_chromium_gn_x64_rel': 'gn_release_trybot',
       'win8_chromium_gn_dbg': 'gn_debug_static_bot_x86',
       'win8_chromium_gn_rel': 'gn_release_trybot_x86',
       'win8_chromium_gn_upload': 'gn_release_bot',
     },
+    'tryserver.v8': {
+      'v8_linux_chromium_gn_rel': 'gn_release_trybot',
+      'v8_android_chromium_gn_dbg': 'android_gn_debug_bot',
+    },
   },
 }