[Cronet] Enforce implementation does not call through API classes

components/cronet/PRESUBMIT.py

Index: components/cronet/PRESUBMIT.py
diff --git a/components/cronet/PRESUBMIT.py b/components/cronet/PRESUBMIT.py
index 6ab05a91f194c922e68ff3ddb19d177f299d19ef..e722191e07c99fa73f09c9b18a68280dd9d61689 100644
--- a/components/cronet/PRESUBMIT.py
+++ b/components/cronet/PRESUBMIT.py
@@ -71,15 +71,25 @@ def _PackageChecks(input_api, output_api):
     return []
 
 
+def _RunUnittests(input_api, output_api):
+  return input_api.canned_checks.RunUnitTestsInDirectory(
+      input_api, output_api, '.', [ r'^.+_unittest\.py$'])
+
+
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_PyLintChecks(input_api, output_api))
   results.extend(
       input_api.canned_checks.CheckPatchFormatted(input_api, output_api))
   results.extend(_PackageChecks(input_api, output_api))
+  results.extend(_RunUnittests(input_api, output_api))
   return results
 
 
+def CheckChangeOnCommit(input_api, output_api):
+  return _RunUnittests(input_api, output_api)
+
+
 def _GetTryMasters(project, change):
   return {
     'master.tryserver.chromium.android': {