rewrite_to_chrome_style: Use constexpr as backdoor to get consistency

tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp

 // Copyright 2015 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.
 //
 // Changes Blink-style names to Chrome-style names. Currently transforms:
 //   fields:
 //     int m_operationCount => int operation_count_
 //   variables (including parameters):
 //     int mySuperVariable => int my_super_variable
 //   constants:
@@ skipping 457 matching lines @@
 
 bool IsProbablyConst(const clang::VarDecl& decl,
                      const clang::ASTContext& context) {
   clang::QualType type = decl.getType();
   if (!type.isConstQualified())
     return false;
 
   if (type.isVolatileQualified())
     return false;
 
+  if (decl.isConstexpr())
+    return true;
+
   // Parameters should not be renamed to |kFooBar| style (even if they are
   // const and have an initializer (aka default value)).
   if (clang::isa<clang::ParmVarDecl>(&decl))
     return false;
 
   // http://google.github.io/styleguide/cppguide.html#Constant_Names
   // Static variables that are const-qualified should use kConstantStyle naming.
   if (decl.getStorageDuration() == clang::SD_Static)
     return true;
 
@@ skipping 1176 matching lines @@
   for (const auto& r : replacements) {
     std::string replacement_text = r.getReplacementText().str();
     std::replace(replacement_text.begin(), replacement_text.end(), '\n', '\0');
     llvm::outs() << "r:::" << r.getFilePath() << ":::" << r.getOffset()
                  << ":::" << r.getLength() << ":::" << replacement_text << "\n";
   }
   llvm::outs() << "==== END EDITS ====\n";
 
   return 0;
 }