Add standalone dawn gclient config

BUG=chromium:875245

Change-Id: Ieed7554c55bab2bc5820cf4ffbbf57b72492b90f
Reviewed-on: https://chromium-review.googlesource.com/1183432Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>

recipes/recipe_modules/gclient/config.py

@@ -412,3 +412,9 @@ def angle(c):
   soln = c.solutions.add()
   soln.name = 'angle'
   soln.url = 'https://chromium.googlesource.com/angle/angle.git'
+
+@config_ctx()
+def dawn(c):
+  soln = c.solutions.add()
+  soln.name = 'dawn'
+  soln.url = 'https://dawn.googlesource.com/dawn.git'

recipes/recipe_modules/gclient/examples/full.py

@@ -21,6 +21,7 @@ TEST_CONFIGS = [
   'crashpad',
   'custom_tabs_client',
   'dart',
+  'dawn',
   'disable_syntax_validation',
   'expect_tests',
   'gerrit_test_cq_normal',