Add presubmit check and automatic update script for ExtensionPermission enum.

extensions/browser/PRESUBMIT.py

Index: extensions/browser/PRESUBMIT.py
diff --git a/extensions/browser/PRESUBMIT.py b/extensions/browser/PRESUBMIT.py
index 29a709b5c807ff63d08b90bba2efb5c61c888067..659c1761e264a12132b2d104f4ef0e357afe9872 100644
--- a/extensions/browser/PRESUBMIT.py
+++ b/extensions/browser/PRESUBMIT.py
@@ -8,6 +8,8 @@ See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details on the presubmit API built into gcl.
 """
 
+import sys
+
 def GetPreferredTryMasters(project, change):
   return {
     'tryserver.chromium': {
@@ -15,294 +17,26 @@ def GetPreferredTryMasters(project, change):
     }
   }
 
-class HistogramValueChecker(object):
-  """Verify that changes to "extension_function_histogram_value.h" are valid.
-
-  See comments at the top of the "extension_function_histogram_value.h" file
-  for what are considered valid changes. There are situations where this script
-  gives false positive warnings, i.e. it warns even though the edit is
-  legitimate. Since the script warns using prompt warnings, the user can always
-  choose to continue. The main point is to attract the attention to all
-  (potentially or not) invalid edits.
-
-  """
-
-  # The name of the file we want to check against
-  LOCAL_PATH = "extensions/browser/extension_function_histogram_value.h"
-
-  # The markers we look for in the above source file as delimiters of the enum
-  # definition.
-  ENUM_START_MARKER = "enum HistogramValue {"
-  ENUM_END_MARKER = "  // Last entry:"
-
-  def __init__(self, input_api, output_api):
-    self.input_api = input_api
-    self.output_api = output_api
-    self.results = []
-
-  class EnumRange(object):
-    """Represents a range of line numbers (1-based)"""
-    def __init__(self, first_line, last_line):
-      self.first_line = first_line
-      self.last_line = last_line
-
-    def Count(self):
-      return self.last_line - self.first_line + 1
-
-    def Contains(self, line_num):
-      return self.first_line <= line_num and line_num <= self.last_line
-
-  def LogInfo(self, message):
-    self.input_api.logging.info(message)
-    return
-
-  def LogDebug(self, message):
-    self.input_api.logging.debug(message)
-    return
-
-  def ComputeEnumRangeInContents(self, contents):
-    """Returns an |EnumRange| object representing the line extent of the
-    HistogramValue enum members in |contents|. The line numbers are 1-based,
-    compatible with line numbers returned by AffectedFile.ChangeContents().
-    |contents| is a list of strings reprenting the lines of a text file.
-
-    If either ENUM_START_MARKER or ENUM_END_MARKER cannot be found in
-    |contents|, returns None and emits detailed warnings about the problem.
-
-    """
-    first_enum_line = 0
-    last_enum_line = 0
-    line_num = 1  # Line numbers are 1-based
-    for line in contents:
-      if line.startswith(self.ENUM_START_MARKER):
-        first_enum_line = line_num + 1
-      elif line.startswith(self.ENUM_END_MARKER):
-        last_enum_line = line_num
-      line_num += 1
-
-    if first_enum_line == 0:
-      self.EmitWarning("The presubmit script could not find the start of the "
-                       "enum definition (\"%s\"). Did the enum definition "
-                       "change?" % self.ENUM_START_MARKER)
-      return None
-
-    if last_enum_line == 0:
-      self.EmitWarning("The presubmit script could not find the end of the "
-                       "enum definition (\"%s\"). Did the enum definition "
-                       "change?" % self.ENUM_END_MARKER)
-      return None
-
-    if first_enum_line >= last_enum_line:
-      self.EmitWarning("The presubmit script located the start of the enum "
-                       "definition (\"%s\" at line %d) *after* its end "
-                       "(\"%s\" at line %d). Something is not quite right."
-                       % (self.ENUM_START_MARKER, first_enum_line,
-                          self.ENUM_END_MARKER, last_enum_line))
-      return None
-
-    self.LogInfo("Line extent of |HistogramValue| enum definition: "
-                 "first_line=%d, last_line=%d."
-                 % (first_enum_line, last_enum_line))
-    return self.EnumRange(first_enum_line, last_enum_line)
-
-  def ComputeEnumRangeInNewFile(self, affected_file):
-    return self.ComputeEnumRangeInContents(affected_file.NewContents())
-
-  def GetLongMessage(self):
-    return str("The file \"%s\" contains the definition of the "
-               "|HistogramValue| enum which should be edited in specific ways "
-               "only - *** read the comments at the top of the header file ***"
-               ". There are changes to the file that may be incorrect and "
-               "warrant manual confirmation after review. Note that this "
-               "presubmit script can not reliably report the nature of all "
-               "types of invalid changes, especially when the diffs are "
-               "complex. For example, an invalid deletion may be reported "
-               "whereas the change contains a valid rename."
-               % self.LOCAL_PATH)
-
-  def EmitWarning(self, message, line_number=None, line_text=None):
-    """Emits a presubmit prompt warning containing the short message
-    |message|. |item| is |LOCAL_PATH| with optional |line_number| and
-    |line_text|.
-
-    """
-    if line_number is not None and line_text is not None:
-      item = "%s(%d): %s" % (self.LOCAL_PATH, line_number, line_text)
-    elif line_number is not None:
-      item = "%s(%d)" % (self.LOCAL_PATH, line_number)
-    else:
-      item = self.LOCAL_PATH
-    long_message = self.GetLongMessage()
-    self.LogInfo(message)
-    self.results.append(
-      self.output_api.PresubmitPromptWarning(message, [item], long_message))
-
-  def CollectRangesInsideEnumDefinition(self, affected_file,
-                                        first_line, last_line):
-    """Returns a list of triplet (line_start, line_end, line_text) of ranges of
-    edits changes. The |line_text| part is the text at line |line_start|.
-    Since it used only for reporting purposes, we do not need all the text
-    lines in the range.
-
-    """
-    results = []
-    previous_line_number = 0
-    previous_range_start_line_number = 0
-    previous_range_start_text = ""
-
-    def addRange():
-      tuple = (previous_range_start_line_number,
-               previous_line_number,
-               previous_range_start_text)
-      results.append(tuple)
-
-    for line_number, line_text in affected_file.ChangedContents():
-      if first_line <= line_number and line_number <= last_line:
-        self.LogDebug("Line change at line number " + str(line_number) + ": " +
-                      line_text)
-        # Start a new interval if none started
-        if previous_range_start_line_number == 0:
-          previous_range_start_line_number = line_number
-          previous_range_start_text = line_text
-        # Add new interval if we reached past the previous one
-        elif line_number != previous_line_number + 1:
-          addRange()
-          previous_range_start_line_number = line_number
-          previous_range_start_text = line_text
-        previous_line_number = line_number
-
-    # Add a last interval if needed
-    if previous_range_start_line_number != 0:
-        addRange()
-    return results
-
-  def CheckForFileDeletion(self, affected_file):
-    """Emits a warning notification if file has been deleted """
-    if not affected_file.NewContents():
-      self.EmitWarning("The file seems to be deleted in the changelist. If "
-                       "your intent is to really delete the file, the code in "
-                       "PRESUBMIT.py should be updated to remove the "
-                       "|HistogramValueChecker| class.");
-      return False
-    return True
-
-  def GetDeletedLinesFromScmDiff(self, affected_file):
-    """Return a list of of line numbers (1-based) corresponding to lines
-    deleted from the new source file (if they had been present in it). Note
-    that if multiple contiguous lines have been deleted, the returned list will
-    contain contiguous line number entries. To prevent false positives, we
-    return deleted line numbers *only* from diff chunks which decrease the size
-    of the new file.
-
-    Note: We need this method because we have access to neither the old file
-    content nor the list of "delete" changes from the current presubmit script
-    API.
-
-    """
-    results = []
-    line_num = 0
-    deleting_lines = False
-    for line in affected_file.GenerateScmDiff().splitlines():
-      # Parse the unified diff chunk optional section heading, which looks like
-      # @@ -l,s +l,s @@ optional section heading
-      m = self.input_api.re.match(
-        r'^@@ \-([0-9]+)\,([0-9]+) \+([0-9]+)\,([0-9]+) @@', line)
-      if m:
-        old_line_num = int(m.group(1))
-        old_size = int(m.group(2))
-        new_line_num = int(m.group(3))
-        new_size = int(m.group(4))
-        line_num = new_line_num
-        # Return line numbers only from diff chunks decreasing the size of the
-        # new file
-        deleting_lines = old_size > new_size
-        continue
-      if not line.startswith('-'):
-        line_num += 1
-      if deleting_lines and line.startswith('-') and not line.startswith('--'):
-        results.append(line_num)
-    return results
-
-  def CheckForEnumEntryDeletions(self, affected_file):
-    """Look for deletions inside the enum definition. We currently use a
-    simple heuristics (not 100% accurate): if there are deleted lines inside
-    the enum definition, this might be a deletion.
-
-    """
-    range_new = self.ComputeEnumRangeInNewFile(affected_file)
-    if not range_new:
-      return False
-
-    is_ok = True
-    for line_num in self.GetDeletedLinesFromScmDiff(affected_file):
-      if range_new.Contains(line_num):
-        self.EmitWarning("It looks like you are deleting line(s) from the "
-                         "enum definition. This should never happen.",
-                         line_num)
-        is_ok = False
-    return is_ok
-
-  def CheckForEnumEntryInsertions(self, affected_file):
-    range = self.ComputeEnumRangeInNewFile(affected_file)
-    if not range:
-      return False
-
-    first_line = range.first_line
-    last_line = range.last_line
-
-    # Collect the range of changes inside the enum definition range.
-    is_ok = True
-    for line_start, line_end, line_text in \
-          self.CollectRangesInsideEnumDefinition(affected_file,
-                                                 first_line,
-                                                 last_line):
-      # The only edit we consider valid is adding 1 or more entries *exactly*
-      # at the end of the enum definition. Every other edit inside the enum
-      # definition will result in a "warning confirmation" message.
-      #
-      # TODO(rpaquay): We currently cannot detect "renames" of existing entries
-      # vs invalid insertions, so we sometimes will warn for valid edits.
-      is_valid_edit = (line_end == last_line - 1)
-
-      self.LogDebug("Edit range in new file at starting at line number %d and "
-                    "ending at line number %d: valid=%s"
-                    % (line_start, line_end, is_valid_edit))
-
-      if not is_valid_edit:
-        self.EmitWarning("The change starting at line %d and ending at line "
-                         "%d is *not* located *exactly* at the end of the "
-                         "enum definition. Unless you are renaming an "
-                         "existing entry, this is not a valid changes, as new "
-                         "entries should *always* be added at the end of the "
-                         "enum definition, right before the 'ENUM_BOUNDARY' "
-                         "entry." % (line_start, line_end),
-                         line_start,
-                         line_text)
-        is_ok = False
-    return is_ok
-
-  def PerformChecks(self, affected_file):
-    if not self.CheckForFileDeletion(affected_file):
-      return
-    if not self.CheckForEnumEntryDeletions(affected_file):
-      return
-    if not self.CheckForEnumEntryInsertions(affected_file):
-      return
+def _CreateHistogramValueChecker(input_api, output_api):
+  original_sys_path = sys.path
 
-  def ProcessHistogramValueFile(self, affected_file):
-    self.LogInfo("Start processing file \"%s\"" % affected_file.LocalPath())
-    self.PerformChecks(affected_file)
-    self.LogInfo("Done processing file \"%s\"" % affected_file.LocalPath())
+  try:
+    sys.path.append(input_api.os_path.join(
+        input_api.PresubmitLocalPath(), '..', '..', 'tools',
+        'strict_enum_value_checker'))
+    from strict_enum_value_checker import StrictEnumValueChecker
+  finally:
+    sys.path = original_sys_path
 
-  def Run(self):
-    for file in self.input_api.AffectedFiles(include_deletes=True):
-      if file.LocalPath() == self.LOCAL_PATH:
-        self.ProcessHistogramValueFile(file)
-    return self.results
+  return StrictEnumValueChecker(input_api, output_api,
+      start_marker='enum HistogramValue {', end_marker='  // Last entry:',
+      path='extensions/browser/extension_function_histogram_value.h')
 
 def CheckChangeOnUpload(input_api, output_api):
   results = []
-  results += HistogramValueChecker(input_api, output_api).Run()
+  results += _CreateHistogramValueChecker(input_api, output_api).Run()
   results += input_api.canned_checks.CheckPatchFormatted(input_api, output_api)
   return results
 
+def CheckChangeOnCommit(input_api, output_api):
+  return _CreateHistogramValueChecker(input_api, output_api).Run()