[android] Change the recommended log tag format to "cr_foo"

PRESUBMIT.py

 # Copyright (c) 2012 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
@@ skipping 1335 matching lines @@
         ' org.chromium.ui.widget.Toast instead.\n'
         'Contact dskiba@chromium.org if you have any questions.',
         errors))
 
   return results
 
 
 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)
+    - Are using a tag that is shorter than 20 characters (error)
   """
   cr_log_import_pattern = input_api.re.compile(
       r'^import org\.chromium\.base\.Log;$', input_api.re.MULTILINE)
   class_in_base_pattern = input_api.re.compile(
       r'^package org\.chromium\.base;$', input_api.re.MULTILINE)
   has_some_log_import_pattern = input_api.re.compile(
       r'^import .*\.Log;$', input_api.re.MULTILINE)
   # Extract the tag from lines like `Log.d(TAG, "*");` or `Log.d("TAG", "*");`
   log_call_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>(.*)")',
+      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 docs/android_logging.md '
             'or contact dgn@chromium.org for more info.')
   sources = lambda x: input_api.FilterSourceFile(x, white_list=(r'.*\.java$',))
 
   tag_decl_errors = []
   tag_length_errors = []
   tag_errors = []
+  tag_with_dot_errors = []
   util_log_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) or
         (class_in_base_pattern.search(file_content) and
             not has_some_log_import_pattern.search(file_content))):
@@ skipping 11 matching lines @@
     else:
       # Report non cr Log function calls in changed lines
       for line_num, line in f.ChangedContents():
         if log_call_pattern.search(line):
           util_log_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_name = match.group('name') if match else None
+      if not tag_name:
         tag_decl_errors.append(f.LocalPath())
-      if len(tag_name) > 23:
+      elif len(tag_name) > 20:
         tag_length_errors.append(f.LocalPath())
+      elif '.' in tag_name:
+        tag_with_dot_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,
+        '"private static final String TAG = "<package tag>".\n'
+        'They will be prepended with "cr_" automatically.\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,
+        '20 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))
 
   if util_log_errors:
     results.append(output_api.PresubmitPromptWarning(
         'Please use org.chromium.base.Log for new logs.\n' + REF_MSG,
         util_log_errors))
 
+  if tag_with_dot_errors:
+    results.append(output_api.PresubmitPromptWarning(
+        'Dot in log tags cause them to be elided in crash reports.\n' + REF_MSG,
+        tag_with_dot_errors))
+
   return results
 
 
 def _CheckForCopyrightedCode(input_api, output_api):
   """Verifies that newly added code doesn't contain copyrighted material
   and is properly licensed under the standard Chromium license.
 
   As there can be false positives, we maintain a whitelist file. This check
   also verifies that the whitelist file is up to date.
   """
@@ skipping 472 matching lines @@
   for master in masters:
     try_config.setdefault(master, {})
     for builder in masters[master]:
       # Do not trigger presubmit builders, since they're likely to fail
       # (e.g. OWNERS checks before finished code review), and we're
       # running local presubmit anyway.
       if 'presubmit' not in builder:
         try_config[master][builder] = ['defaulttests']
 
   return try_config