mb: Add src-side changes for a new "win_clang" bot.

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 a map of buildbot master names -> buildbot builder names ->
   # config names (where each config name is a key in the 'configs' dict,
   # below). MB uses this dict to look up which config to use for a given bot.
   'masters': {
     # Take care when changing any of these builders to ensure that you do not
@@ skipping 192 matching lines @@
       'Chromium_iOS_Simulator_(dbg)': 'ios_gyp',
       'CrWinClang64(dbg)': 'win_clang_debug_bot',
       'Libfuzzer Upload Linux ASan': 'gn_release_libfuzzer_asan',
       'Libfuzzer Upload Linux MSan': 'gn_release_libfuzzer_msan',
       'Libfuzzer Upload Linux UBSan': 'gn_release_libfuzzer_ubsan',
       'Linux ARM': 'swarming_gyp_release_bot_arm',
       'Site Isolation Linux': 'gn_release_trybot',
       'Site Isolation Win': 'gyp_release_trybot_x64',
       'Win LKGR (DrM 64)': 'gn_release_drmemory_drfuzz',
       'Win LKGR (DrM)': 'gn_release_drmemory_drfuzz_x86',
+      'WinClang': 'win_clang_debug_bot',
     },
 
     'chromium.gpu': {
       'Android Debug (Nexus 5)': 'tbd',
       'Android Debug (Nexus 6)': 'tbd',
       'Android Debug (Nexus 9)': 'tbd',
       'GPU Mac Builder': 'tbd',
       'GPU Mac Builder (dbg)': 'tbd',
       'GPU Win Builder': 'tbd',
       'GPU Win Builder (dbg)': 'tbd',
@@ skipping 595 matching lines @@
       'win_optional_gpu_tests_rel': 'tbd',
 
       'win8_chromium_gn_dbg': 'gn_debug_bot_minimal_symbols_x86',
       'win8_chromium_gn_upload': 'gn_release_bot_minimal_symbols_x86',
       'win8_chromium_ng': 'gn_release_trybot_x86',
       'win_chromium_clang_upload': 'gn_release_bot',
       'win_chromium_gn_x64_dbg': 'gn_debug_bot_minimal_symbols',
       'win_chromium_gn_x64_rel': 'gn_release_trybot',
       'win_chromium_x64_rel_ng': 'gn_release_trybot',
       'win10_chromium_x64_rel_ng': 'gn_release_trybot',
+      'win_clang': 'win_clang_debug_bot',
       'win_clang_x64_dbg': 'win_clang_debug_bot',
       'win_pgo': 'gyp_official_winpgo',
     },
 
     'tryserver.v8': {
       'v8_android_chromium_gn_dbg': 'android_gn_debug_bot',
       'v8_linux_blink_rel': 'swarming_gn_release_trybot_minimal_symbols_x64',
       'v8_linux_chromium_gn_rel': 'gn_release_trybot',
     },
   },
@@ skipping 931 matching lines @@
       'gn_args': 'is_component_build=true enable_iterator_debugging=false',
       'gyp_defines': 'component=shared_library build_for_tool=drmemory',
     },
 
     'valgrind': {
       # TODO: add gn_args for 'build_for_tool=memcheck'
       'gyp_defines': 'build_for_tool=memcheck',
     }
   },
 }