Add Linux ARM builder to main waterfall

scripts/slave/recipe_modules/chromium/chromium_linux.py

 # Copyright 2014 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.
 
 from . import steps
 
 SPEC = {
   'settings': {
     'build_gs_bucket': 'chromium-linux-archive',
   },
   'builders': {
+    'Linux ARM': {
+      'chromium_config': 'chromium',
+      'gclient_config': 'chromium',
+      'chromium_config_kwargs': {
+        'BUILD_CONFIG': 'Release',
+        'TARGET_ARCH': 'arm',
+        'TARGET_BITS': 32,
+      },
+      'bot_type': 'builder',
+      'compile_targets': [
+        'all',
+      ],
+      'use_isolate': True,
+      'testing': {
+        'platform': 'linux',
+      },
+    },
     'Linux Builder': {
       'chromium_config': 'chromium',
       'gclient_config': 'chromium',
       'chromium_config_kwargs': {
         'BUILD_CONFIG': 'Release',
         'TARGET_BITS': 64,
       },
       'bot_type': 'builder',
       'compile_targets': [
         'chromium_swarm_tests',
@@ skipping 401 matching lines @@
         'TARGET_BITS': 32,
         'TARGET_PLATFORM': 'android',
       },
       'android_config': 'cast_builder',
       'testing': {
         'platform': 'linux',
       },
     },
   },
 }