Go back to unconditionally skipping fields in generated files.

bartekn@ has kindly identified r819402 as a source of performance
regression in rewriter runtime - the numbers below represent the time
(in minutes) of the 1st pass, 2nd pass and the total rewrite runtime:
Before crrev.com/c/2488744: 89, 89, 196
After crrev.com/c/2488744: 167, 165, 349

To improve rewrite performance, this CL goes back to unconditionally
skipping fields in generated files (i.e. partially reverts
crrev.com/c/2488744).  This is okay, because we have already gathered
and stored the statistics about the skipped fields in generated files
here:
https://drive.google.com/file/d/1L27GU76qZZspq-AVLdIamsl61FKazPuf/view?usp=sharing

Bug: 819402
Change-Id: Ie00b326c800ee68fabe64fd2ad12f18e69bc8f0f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2507233Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Bartek Nowierski <bartekn@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822790}

tools/clang/rewrite_raw_ptr_fields/RewriteRawPtrFields.cpp

@@ -906,7 +906,7 @@ int main(int argc, const char* argv[]) {
       fieldDecl(
           allOf(hasType(supported_pointer_types_matcher),
                 unless(anyOf(isExpansionInSystemHeader(), isInExternCContext(),
-                             isInThirdPartyLocation(),
+                             isInThirdPartyLocation(), isInGeneratedLocation(),
                              isInLocationListedInFilterFile(&paths_to_exclude),
                              isFieldDeclListedInFilterFile(&fields_to_exclude),
                              implicit_field_decl_matcher))))
@@ -1089,15 +1089,6 @@ int main(int argc, const char* argv[]) {
   FilteredExprWriter global_destructor_writer(&output_helper, "global-scope");
   match_finder.addMatcher(global_destructor_matcher, &global_destructor_writer);
 
-  // Matches rewritable fields in generated code - see the testcase in
-  // tests/gen-generated-code-test.cc
-  auto field_in_generated_code_matcher =
-      fieldDecl(allOf(field_decl_matcher, isInGeneratedLocation()));
-  FilteredExprWriter field_in_generated_code_writer(&output_helper,
-                                                    "generated-code");
-  match_finder.addMatcher(field_in_generated_code_matcher,
-                          &field_in_generated_code_writer);
-
   // Matches CXXRecordDecls with a deleted operator new - e.g.
   // StructWithNoOperatorNew below:
   //     struct StructWithNoOperatorNew {

tools/clang/rewrite_raw_ptr_fields/tests/gen-generated-code-expected.txt

-==== BEGIN EDITS ====
-include-user-header:::/usr/local/google/home/lukasza/src/chromium4/src/tools/clang/rewrite_raw_ptr_fields/tests/gen/generated_header.h:::-1:::-1:::base/memory/checked_ptr.h
-r:::/usr/local/google/home/lukasza/src/chromium4/src/tools/clang/rewrite_raw_ptr_fields/tests/gen/generated_header.h:::552:::5:::CheckedPtr<int> 
-r:::/usr/local/google/home/lukasza/src/chromium4/src/tools/clang/rewrite_raw_ptr_fields/tests/gen/generated_header.h:::570:::11:::CheckedPtr<SomeClass> 
-==== END EDITS ====
-==== BEGIN FIELD FILTERS ====
-GeneratedStruct::ptr_field  # generated-code
-GeneratedStruct::ptr_field2  # generated-code
-==== END FIELD FILTERS ====

tools/clang/rewrite_raw_ptr_fields/tests/gen-generated-code-test.cc

-// Copyright 2020 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.
-
-// This file (and other gen-*-test.cc files) tests generation of output for
-// --field-filter-file and therefore the expectations file
-// (gen-char-expected.txt) needs to be compared against the raw output of the
-// rewriter (rather than against the actual edits result).  This makes the test
-// incompatible with other tests, which require passing --apply-edits switch to
-// test_tool.py and so to disable the test it is named *-test.cc rather than
-// *-original.cc.
-//
-// To run the test use tools/clang/rewrite_raw_ptr_fields/tests/run_all_tests.py
-
-// Fields in "gen/generated_header.h" should be emitted be emitted as candidates
-// for the --field-filter-file.
-#include "gen/generated_header.h"