Remove presubmit check for DISALLOW_* macros

Before C++11, we were using a hack to disable copy constructors or copy
assignment by declaring the methods private and not implementing them.
This hack required the respective macros to be placed in the private:
declarations of a class.
The macros have switched to use the C++11 "= delete" syntax some time
ago in both v8 and chromium:
https://codereview.chromium.org/1123723003/
https://codereview.chromium.org/2017213002

Also the comments are now updated, since the macros do not need to be
in the private: declarations any more:
https://chromium-review.googlesource.com/c/577687
https://chromium-review.googlesource.com/c/578027

This change also removes the presubmit check that checked that the
macros are only used in the private declarations.

cpplint/cpplint.py

@@ -3072,36 +3072,6 @@ def CheckComment(line, filename, linenum, next_line_start, error):
               'Should have a space between // and comment')
 
 
-def CheckAccess(filename, clean_lines, linenum, nesting_state, error):
-  """Checks for improper use of DISALLOW* macros.
-
-  Args:
-    filename: The name of the current file.
-    clean_lines: A CleansedLines instance containing the file.
-    linenum: The number of the line to check.
-    nesting_state: A NestingState instance which maintains information about
-                   the current stack of nested blocks being parsed.
-    error: The function to call with any errors found.
-  """
-  line = clean_lines.elided[linenum]  # get rid of comments and strings
-
-  matched = Match((r'\s*(DISALLOW_COPY_AND_ASSIGN|'
-                   r'DISALLOW_IMPLICIT_CONSTRUCTORS)'), line)
-  if not matched:
-    return
-  if nesting_state.stack and isinstance(nesting_state.stack[-1], _ClassInfo):
-    if nesting_state.stack[-1].access != 'private':
-      error(filename, linenum, 'readability/constructors', 3,
-            '%s must be in the private: section' % matched.group(1))
-
-  else:
-    # Found DISALLOW* macro outside a class declaration, or perhaps it
-    # was used inside a function when it should have been part of the
-    # class declaration.  We could issue a warning here, but it
-    # probably resulted in a compiler error already.
-    pass
-
-
 def CheckSpacing(filename, clean_lines, linenum, nesting_state, error):
   """Checks for the correctness of various spacing issues in the code.
 
@@ -4338,7 +4308,6 @@ def CheckStyle(filename, clean_lines, linenum, file_extension, nesting_state,
   CheckBraces(filename, clean_lines, linenum, error)
   CheckTrailingSemicolon(filename, clean_lines, linenum, error)
   CheckEmptyBlockBody(filename, clean_lines, linenum, error)
-  CheckAccess(filename, clean_lines, linenum, nesting_state, error)
   CheckSpacing(filename, clean_lines, linenum, nesting_state, error)
   CheckOperatorSpacing(filename, clean_lines, linenum, error)
   CheckParenthesisSpacing(filename, clean_lines, linenum, error)