Add presubmit check for header inclusion violation.

This warns about include directives of inline headers within normal
header files. Note that this warning should not close the tree or
prevent the CQ from landing the patch.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/1293273005

Cr-Commit-Position: refs/heads/master@{#30228}

PRESUBMIT.py

@@ -141,6 +141,39 @@ def _CheckUnwantedDependencies(input_api, output_api):
   return results
 
 
+def _CheckNoInlineHeaderIncludesInNormalHeaders(input_api, output_api):
+  """Attempts to prevent inclusion of inline headers into normal header
+  files. This tries to establish a layering where inline headers can be
+  included by other inline headers or compilation units only."""
+  file_inclusion_pattern = r'(?!.+-inl\.h).+\.h'
+  include_directive_pattern = input_api.re.compile(r'#include ".+-inl.h"')
+  include_warning = (
+    'You might be including an inline header (e.g. foo-inl.h) within a\n'
+    'normal header (e.g. bar.h) file.  Can you avoid introducing the\n'
+    '#include?  The commit queue will not block on this warning.')
+
+  def FilterFile(affected_file):
+    black_list = (_EXCLUDED_PATHS +
+                  input_api.DEFAULT_BLACK_LIST)
+    return input_api.FilterSourceFile(
+      affected_file,
+      white_list=(file_inclusion_pattern, ),
+      black_list=black_list)
+
+  problems = []
+  for f in input_api.AffectedSourceFiles(FilterFile):
+    local_path = f.LocalPath()
+    for line_number, line in f.ChangedContents():
+      if (include_directive_pattern.search(line)):
+        problems.append(
+          '%s:%d\n    %s' % (local_path, line_number, line.strip()))
+
+  if problems:
+    return [output_api.PresubmitPromptOrNotify(include_warning, problems)]
+  else:
+    return []
+
+
 def _CheckNoProductionCodeUsingTestOnlyFunctions(input_api, output_api):
   """Attempts to prevent use of functions intended only for testing in
   non-testing code. For now this is just a best-effort implementation
@@ -195,6 +228,8 @@ def _CommonChecks(input_api, output_api):
   results.extend(_CheckUnwantedDependencies(input_api, output_api))
   results.extend(
       _CheckNoProductionCodeUsingTestOnlyFunctions(input_api, output_api))
+  results.extend(
+      _CheckNoInlineHeaderIncludesInNormalHeaders(input_api, output_api))
   return results