Presubmit check to verify up-to-date generated Go files.

Add presubmit detection of generated Go files that need to be
updated.

Bug: skia:13630
Change-Id: I3bc07e69f795697fb4a1d93564ce120b1eb25ca9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/569096
Reviewed-by: Kevin Lubick <[email protected]>
Commit-Queue: Chris Mumford <[email protected]>

PRESUBMIT.py

@@ -242,6 +242,15 @@ def _RegenerateAllExamplesCPP(input_api, output_api):
     )]
   return results
 
+
+def _CheckOutOfDateGeneratedGo(input_api, output_api):
+  """Make sure that all generated Go source are current."""
+  for affected_file in input_api.AffectedFiles(include_deletes=True):
+    affected_file_path = affected_file.LocalPath()
+    if affected_file_path.endswith('.go'):
+      return _RunCommandAndCheckGitDiff(output_api, ['go', 'generate', './...'])
+  return []  # No modified Go source files.
+
 def _CheckBazelBUILDFiles(input_api, output_api):
   """Makes sure our BUILD.bazel files are compatible with G3."""
   results = []
@@ -388,6 +397,7 @@ def _CommonChecks(input_api, output_api):
   results.extend(_CheckGitConflictMarkers(input_api, output_api))
   results.extend(_RegenerateAllExamplesCPP(input_api, output_api))
   results.extend(_CheckBazelBUILDFiles(input_api, output_api))
+  results.extend(_CheckOutOfDateGeneratedGo(input_api, output_api))
   return results