[weblayer] Add presubmit for AIDL changes

If an AIDL file changes (comment and whitespace changes are ignored) then
assert that the API version number is incremented by 1.

Change-Id: Id7f3a17f9ab2244946d0cf12d7f0af48187172ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879462
Commit-Queue: Tobias Sargeant <tobiasjs@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710964}

weblayer/PRESUBMIT.py

+# Copyright 2019 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Presubmit tests for weblayer.
+
+Runs various style checks before upload.
+"""
+
+import re
+
+WEBLAYER_VERSION_PATH = (
+    'weblayer/browser/java/org/chromium/weblayer_private/aidl/' +
+    'WebLayerVersion.java')
+
+
+def CheckChangeOnUpload(input_api, output_api):
+  results = []
+  results.extend(_CheckAIDLVersionBump(input_api, output_api))
+  return results
+
+
+def _Canonicalize(lines):
+  """Strip comments, and convert all whitespace to single spaces."""
+
+  def _CanonicalizeLine(line):
+    line = re.sub(r'//,*', '', line)
+    line = re.sub(r'\s+', ' ', line)
+    return line
+
+  return re.sub(r'\s*/\*.*?\*/\s*', ' ', ''.join(map(_CanonicalizeLine, lines)))
+
+
+def _CheckAIDLVersionBump(input_api, output_api):
+  """Any change to an AIDL file must be accompanied by a version code bump."""
+
+  def AIDLFiles(affected_file):
+    return input_api.FilterSourceFile(affected_file, white_list=(r'.*\.aidl$',))
+
+  aidl_changes = []
+  for f in input_api.AffectedSourceFiles(AIDLFiles):
+    old_contents = _Canonicalize(f.OldContents())
+    new_contents = _Canonicalize(f.NewContents())
+    if old_contents != new_contents:
+      aidl_changes.append((f.LocalPath(), f.Action()))
+
+  if not aidl_changes:
+    return []
+
+  aidl_changes = '\n'.join(
+      '  {1} {0}'.format(path, action) for path, action in aidl_changes)
+
+  def VersionFile(affected_file):
+    return input_api.FilterSourceFile(
+        affected_file, white_list=(WEBLAYER_VERSION_PATH,))
+
+  changed_version_file = list(input_api.AffectedSourceFiles(VersionFile))
+
+  if not changed_version_file:
+    return [
+        output_api.PresubmitPromptWarning(
+            'Commit contains AIDL changes,' +
+            ' but does not change WebLayerVersion.java\n' + aidl_changes)
+    ]
+
+  assert len(changed_version_file) == 1
+
+  old_contents = _Canonicalize(changed_version_file[0].OldContents())
+  new_contents = _Canonicalize(changed_version_file[0].NewContents())
+
+  m_old = re.search(r'sVersionNumber\s*=\s*(.*?);', old_contents)
+  m_new = re.search(r'sVersionNumber\s*=\s*(.*?);', new_contents)
+  if m_old and m_new and m_old.group(1) == m_new.group(1):
+    return [
+        output_api.PresubmitPromptWarning(
+            'Commit contains AIDL changes,' +
+            ' but does not change WebLayerVersion.sVersionNumber\n' +
+            aidl_changes)
+    ]
+
+  return []

weblayer/browser/java/org/chromium/weblayer_private/aidl/WebLayerVersion.java

@@ -4,5 +4,9 @@
 
 package org.chromium.weblayer_private.aidl;
 
-/** Holds the current version number of WebLayer. */
+/**
+ * Holds the current version number of WebLayer.
+ *
+ * Whenever any AIDL file is changed, sVersionNumber must be incremented.
+ * */
 public final class WebLayerVersion { public static int sVersionNumber = 3; }