Add a copy of the "WinClang64 (dbg)" bot to the main waterfall.

scripts/slave/recipe_modules/chromium_tests/chromium_win.py

Index: scripts/slave/recipe_modules/chromium_tests/chromium_win.py
diff --git a/scripts/slave/recipe_modules/chromium_tests/chromium_win.py b/scripts/slave/recipe_modules/chromium_tests/chromium_win.py
index f1de7014c4907ac5df8ae77eb32db734cab0a8d1..1dc4ff063adb38aa9fd0127d8ed8fcfdbc794a2d 100644
--- a/scripts/slave/recipe_modules/chromium_tests/chromium_win.py
+++ b/scripts/slave/recipe_modules/chromium_tests/chromium_win.py
@@ -282,5 +282,28 @@ SPEC = {
         'platform': 'win',
       },
     },
+    'WinClang64 (dbg)': {
+      'chromium_config': 'chromium_win_clang',
+      'chromium_apply_config': ['mb'],
+      'gclient_config': 'chromium',
+      'chromium_config_kwargs': {
+        'BUILD_CONFIG': 'Debug',
+        'TARGET_PLATFORM': 'win',
+        'TARGET_BITS': 64,
+      },
+      'compile_targets': [
+        'all',
+      ],
+      # Recipes builds Debug builds with component=shared_library by default.
+      'bot_type': 'builder',
+      'testing': {
+        'platform': 'win',
+      },
+      'use_isolate': True,
+      'enable_swarming': True,
+      # Workaround so that recipes doesn't add random build targets to our
+      # compile line. We want to build everything.
+      'add_tests_as_compile_targets': False,
+    },
   },
 }