Revert of Clang plugin to check that unstable types are not used in IPC.

tools/clang/plugins/CheckIPCVisitor.h

Index: tools/clang/plugins/CheckIPCVisitor.h
diff --git a/tools/clang/plugins/CheckIPCVisitor.h b/tools/clang/plugins/CheckIPCVisitor.h
deleted file mode 100644
index 1ba488eb740cd207811bbb7f1d2c81b32031fc13..0000000000000000000000000000000000000000
--- a/tools/clang/plugins/CheckIPCVisitor.h
+++ /dev/null
@@ -1,101 +0,0 @@
-// Copyright (c) 2016 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 check ensures that 32/64-bit unstable types are not used in IPC.
-//
-// A type (or typedef) is unstable if it changes size between 32/ 64-bit
-// platforms. However, it's impossible to accurately identify unstable
-// typedefs, because their definitions rely on the preprocessor. For
-// example uintptr_t is either unsigned int or unsigned long.
-//
-// So we're not trying to be accurate, and just blacklisting some types
-// that are known to be unstable:
-// 1. Types: long / unsigned long (but not typedefs to)
-// 2. Typedefs: intmax_t, uintmax_t, intptr_t, uintptr_t, wint_t,
-//    size_t, rsize_t, ssize_t, ptrdiff_t, dev_t, off_t, clock_t,
-//    time_t, suseconds_t (including typedefs to)
-//
-// Additionally, templates referencing blacklisted types (e.g. vector<long>)
-// are also blacklisted.
-//
-// Blacklisted types are checked in:
-// 1. IPC::WriteParam() calls
-// 2. IPC::CheckedTuple<> specializations
-//
-
-#ifndef TOOLS_CLANG_PLUGINS_CHECKIPC_VISITOR_H_
-#define TOOLS_CLANG_PLUGINS_CHECKIPC_VISITOR_H_
-
-#include <vector>
-
-#include "clang/AST/AST.h"
-#include "clang/AST/ASTConsumer.h"
-#include "clang/AST/RecursiveASTVisitor.h"
-#include "clang/Frontend/CompilerInstance.h"
-#include "llvm/ADT/StringSet.h"
-
-namespace chrome_checker {
-
-class CheckIPCVisitor {
- public:
-  explicit CheckIPCVisitor(clang::CompilerInstance& compiler);
-
-  void set_context(clang::ASTContext* context) { context_ = context; }
-
-  bool should_visit_template_instantiations() const { return true; }
-
-  void BeginDecl(clang::Decl* decl);
-  void EndDecl();
-  void VisitTemplateSpecializationType(
-      clang::TemplateSpecializationType* spec);
-  void VisitCallExpr(clang::CallExpr* call_expr);
-
- private:
-  // ValidateXXX functions return false if validation failed and diagnostic
-  // was reported. They return true otherwise (not applicable / validation
-  // succeeded).
-
-  bool ValidateWriteParam(const clang::CallExpr* call_expr);
-  bool ValidateWriteParamSignature(const clang::CallExpr* call_expr);
-  bool ValidateWriteParamArgument(const clang::Expr* arg_expr);
-  bool ValidateCheckedTuple(
-      const clang::TemplateSpecializationType* spec);
-
-  template <typename T>
-  const T* GetParentDecl() const;
-
-  bool IsBlacklistedType(clang::QualType type) const;
-  bool IsBlacklistedTypedef(const clang::TypedefNameDecl* tdef) const;
-
-  struct CheckDetails {
-    clang::QualType entry_type;
-    clang::QualType exit_type;
-    llvm::SmallVector<const clang::TypedefType*, 5> typedefs;
-  };
-
-  bool CheckType(clang::QualType type, CheckDetails* details) const;
-  bool CheckIntegerType(clang::QualType type, CheckDetails* details) const;
-  bool CheckTemplateArgument(const clang::TemplateArgument& arg,
-                             CheckDetails* details) const;
-
-  void ReportCheckError(const CheckDetails& details,
-                        clang::SourceLocation loc,
-                        unsigned error);
-
-  clang::CompilerInstance& compiler_;
-  clang::ASTContext* context_;
-
-  unsigned error_write_param_bad_type_;
-  unsigned error_tuple_bad_type_;
-  unsigned error_write_param_bad_signature_;
-  unsigned note_see_here_;
-
-  std::vector<const clang::Decl*> decl_stack_;
-
-  llvm::StringSet<> blacklisted_typedefs_;
-};
-
-}  // namespace chrome_checker
-
-#endif  // TOOLS_CLANG_PLUGINS_CHECKIPC_VISITOR_H_