Add Clang ToT builder for iOS

scripts/slave/recipe_modules/chromium/config.py

 # Copyright 2013 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.
 
 import pipes
 
 from slave.recipe_config import config_item_context, ConfigGroup
 from slave.recipe_config import Dict, List, Single, Static, Set, BadConf
 from slave.recipe_config_types import Path
 
@@ skipping 659 matching lines @@
   c.compile_py.xcode_sdk = 'iphoneos7.1'
 
 @config_ctx(includes=['ios', 'ninja'])
 def chromium_ios_ninja(c):
   c.build_config_fs += '-iphoneos'
   c.compile_py.default_targets = ['All']
 
   gyp_defs = c.gyp_env.GYP_DEFINES
   gyp_defs['clang_xcode'] = 0
 
+@config_ctx(includes=['chromium_ios_ninja'])
+def clang_tot_ios(c):
+  # Use ToT Clang.
+  c.env.LLVM_FORCE_HEAD_REVISION = 'YES'
+
 @config_ctx(includes=['ios'])
 def chromium_ios_simulator(c):
   c.compile_py.build_tool = 'xcode'
   c.compile_py.default_targets = ['All']
   c.compile_py.xcode_sdk = 'iphonesimulator7.1'
 
 @config_ctx(includes=['chromium', 'official'])
 def chromium_official(c):
   # TODO(phajdan.jr): Unify compile targets used by official builders.
   if c.TARGET_PLATFORM == 'win':
@@ skipping 111 matching lines @@
 def chromium_deterministic_build(c):
   c.gyp_env.GYP_DEFINES['dont_embed_build_metadata'] = 1
 
 @config_ctx()
 def chromium_mac_sdk_10_10(c):
   c.gyp_env.GYP_DEFINES['mac_sdk_min='] = '10.10'
 
 @config_ctx(includes=['chromium_clang'])
 def cast_linux(c):
   c.gyp_env.GYP_DEFINES['chromecast'] = 1