[Android log] Promote using hardcoded string tags

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 4d5c85391b6477f644b3edfabd28599e29f8dd53..515da1d0b38a040556c54eb010c94bdab8f4ae98 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -1304,6 +1304,77 @@ def _CheckJavaStyle(input_api, output_api):
       black_list=_EXCLUDED_PATHS + input_api.DEFAULT_BLACK_LIST)
 
 
+def _CheckAndroidCrLogUsage(input_api, output_api):
+  """Checks that new logs using org.chromium.base.Log:
+    - Are using 'TAG' as variable name for the tags (warn)
+    - Are using the suggested name format for the tags: "cr.<PackageTag>" (warn)
+    - Are using a tag that is shorter than 23 characters (error)
+  """
+  cr_log_import_pattern = input_api.re.compile(
+      r'^import org\.chromium\.base\.Log;$', input_api.re.MULTILINE);
+  # Extract the tag from lines like `Log.d(TAG, "*");` or `Log.d("TAG", "*");`
+  cr_log_pattern = input_api.re.compile(r'^\s*Log\.\w\((?P<tag>\"?\w+\"?)\,')
+  log_decl_pattern = input_api.re.compile(
+      r'^\s*private static final String TAG = "(?P<name>(.*)")',
+      input_api.re.MULTILINE)
+  log_name_pattern = input_api.re.compile(r'^cr[.\w]*')
+
+  REF_MSG = ('See base/android/java/src/org/chromium/base/README_logging.md '
+            'or contact dgn@chromium.org for more info.')
+  sources = lambda x: input_api.FilterSourceFile(x, white_list=(r'.*\.java$',))
+  tag_errors = []
+  tag_decl_errors = []
+  tag_length_errors = []
+
+  for f in input_api.AffectedSourceFiles(sources):
+    file_content = input_api.ReadFile(f)
+    has_modified_logs = False
+
+    # Per line checks
+    if cr_log_import_pattern.search(file_content):
+      for line_num, line in f.ChangedContents():
+
+        # Check if the new line is doing some logging
+        match = cr_log_pattern.search(line)
+        if match:
+          has_modified_logs = True
+
+          # Make sure it uses "TAG"
+          if not match.group('tag') == 'TAG':
+            tag_errors.append("%s:%d" % (f.LocalPath(), line_num))
+
+    # Per file checks
+    if has_modified_logs:
+      # Make sure the tag is using the "cr" prefix and is not too long
+      match = log_decl_pattern.search(file_content)
+      tag_name = match.group('name') if match else ''
+      if not log_name_pattern.search(tag_name ):
+        tag_decl_errors.append(f.LocalPath())
+      if len(tag_name) > 23:
+        tag_length_errors.append(f.LocalPath())
+
+  results = []
+  if tag_decl_errors:
+    results.append(output_api.PresubmitPromptWarning(
+        'Please define your tags using the suggested format: .\n'
+        '"private static final String TAG = "cr.<package tag>".\n' + REF_MSG,
+        tag_decl_errors))
+
+  if tag_length_errors:
+    results.append(output_api.PresubmitError(
+        'The tag length is restricted by the system to be at most '
+        '23 characters.\n' + REF_MSG,
+        tag_length_errors))
+
+  if tag_errors:
+    results.append(output_api.PresubmitPromptWarning(
+        'Please use a variable named "TAG" for your log tags.\n' + REF_MSG,
+        tag_errors))
+
+  return results
+
+
+# TODO(dgn): refactor with _CheckAndroidCrLogUsage
 def _CheckNoNewUtilLogUsage(input_api, output_api):
   """Checks that new logs are using org.chromium.base.Log."""
 
@@ -1456,6 +1527,14 @@ def _CheckNoDeprecatedJS(input_api, output_api):
   return results
 
 
+def _AndroidSpecificOnUploadChecks(input_api, output_api):
+  """Groups checks that target android code."""
+  results = []
+  results.extend(_CheckNoNewUtilLogUsage(input_api, output_api))
+  results.extend(_CheckAndroidCrLogUsage(input_api, output_api))
+  return results
+
+
 def _CommonChecks(input_api, output_api):
   """Checks common to both upload and commit."""
   results = []
@@ -1728,7 +1807,7 @@ def CheckChangeOnUpload(input_api, output_api):
   results.extend(
       input_api.canned_checks.CheckGNFormatted(input_api, output_api))
   results.extend(_CheckUmaHistogramChanges(input_api, output_api))
-  results.extend(_CheckNoNewUtilLogUsage(input_api, output_api))
+  results.extend(_AndroidSpecificOnUploadChecks(input_api, output_api))
   return results