Reland [Presubmit tests] Warn when new source files are not added to GN/GYPi files.

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index e2e042336926e54a01f47dd33769c9a534c7c92c..310091e538370de4ed866daddb207ab714bd20e1 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -1946,6 +1946,52 @@ def _AndroidSpecificOnUploadChecks(input_api, output_api):
   results.extend(_CheckAndroidToastUsage(input_api, output_api))
   return results
 
+def _CheckNewSourceFileAddedToGnGypi(input_api, output_api):
+   """Checks new source code files were added to GN/GYPi files"""
+   new_source_files = []
+   gn_gypi_files = []
+
+   """ Get lists of new source code files and GN/GYPi files in the commit"""
+   for f in input_api.AffectedFiles():
+     if f.LocalPath().endswith(('.gn', '.gypi')):
+       gn_gypi_files.append(f)
+       continue
+     if f.LocalPath().endswith(('.h', '.c', '.cc', '.m', '.mm', '.java')):
+        if f.Action() == 'A':
+          new_source_files.append(f.LocalPath())
+
+   if not new_source_files:
+     return []
+
+   if not gn_gypi_files:
+     return [output_api.PresubmitPromptWarning('The following new'
+         ' source code files must be added to GN/GYPI files:\n    ' +
+         '\n    '.join(new_source_files))]
+
+   """Get a list of new source code files that CAN BE FOUND in the GN/GYPI
+      files"""
+   source_files_listed = []
+   for f in new_source_files:
+     head, sep, tail = f.rpartition('/')
+     source_file_match_pattern = tail
+     for g in gn_gypi_files:
+       for line in g.GenerateScmDiff().splitlines():
+         if line.endswith((source_file_match_pattern + '",',
+                           source_file_match_pattern + '\',')):
+           source_files_listed.append(f)
+           break
+
+   """Remove files, which has been found in the GN files, from the list"""
+   for f in source_files_listed:
+     if f in new_source_files:
+       new_source_files.remove(f)
+
+   if new_source_files:
+     return [output_api.PresubmitPromptWarning('The following new'
+         ' source code files must be added to GN/GYPI files:\n    ' +
+         '\n    '.join(new_source_files))]
+
+   return []
 
 def _CommonChecks(input_api, output_api):
   """Checks common to both upload and commit."""
@@ -2208,6 +2254,7 @@ def CheckChangeOnUpload(input_api, output_api):
       input_api.canned_checks.CheckGNFormatted(input_api, output_api))
   results.extend(_CheckUmaHistogramChanges(input_api, output_api))
   results.extend(_AndroidSpecificOnUploadChecks(input_api, output_api))
+  results.extend(_CheckNewSourceFileAddedToGnGypi(input_api, output_api))
   return results