Add IGNORE_DEPS_CHANGES flag and coverage builder.

scripts/slave/recipe_modules/chromium_tests/builders.py

Index: scripts/slave/recipe_modules/chromium_tests/builders.py
diff --git a/scripts/slave/recipe_modules/chromium_tests/builders.py b/scripts/slave/recipe_modules/chromium_tests/builders.py
index 12fc443dcb7860c32dad2b9404e4d756bcb010fa..45e960aeb763118c9f5db91aa38d28bbf4c2886b 100644
--- a/scripts/slave/recipe_modules/chromium_tests/builders.py
+++ b/scripts/slave/recipe_modules/chromium_tests/builders.py
@@ -60,6 +60,9 @@ BUILDERS = freeze({
   # Note that this master is not real, and consequently this build configuration
   # will never be used in production.
   'bot_update.always_on': {
+    'settings': {
+      'build_gs_bucket': '!fake-coverage-bucket',
+    },
     'builders': {
       'coverage_clobber': {
         'chromium_config': 'chromium',
@@ -71,6 +74,24 @@ BUILDERS = freeze({
         },
         'gs_bucket': 'invalid',
       },
+
+      # Add a coverage builder to exercise configs that are leveraged in other
+      # recipe collections to build chrome packages:
+      # - "ignore_deps_changes"
+      'Package Builder (Coverage)': {
+        'chromium_config': 'chromium',
+        'chromium_apply_config': ['chromeos', 'ninja_confirm_noop',
+                                  'ignore_deps_changes', 'mb'],
+        'gclient_config': 'chromium',
+        'chromium_config_kwargs': {
+          'BUILD_CONFIG': 'Debug',
+          'TARGET_BITS': 64,
+        },
+        'bot_type': 'builder',
+        'testing': {
+          'platform': 'linux',
+        },
+      },
     },
   },
 })