Add curly brackets to list of characters that gn needs to escape

tools/gn/escape_unittest.cc

 // Copyright (c) 2013 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.
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/escape.h"
 
 TEST(Escape, Ninja) {
   EscapeOptions opts;
   opts.mode = ESCAPE_NINJA;
@@ skipping 31 matching lines @@
 TEST(Escape, PosixCommand) {
   EscapeOptions opts;
   opts.mode = ESCAPE_NINJA_COMMAND;
   opts.platform = ESCAPE_PLATFORM_POSIX;
 
   // : and $ ninja escaped with $. Then Shell-escape backslashes and quotes.
   EXPECT_EQ("a$:\\$ \\\"\\$$\\\\b", EscapeString("a: \"$\\b", opts, nullptr));
 
   // Some more generic shell chars.
   EXPECT_EQ("a_\\;\\<\\*b", EscapeString("a_;<*b", opts, nullptr));
+
+  // Curly braces must be escaped to avoid brace expansion on systems using
+  // bash as default shell..
+  EXPECT_EQ("\\{a,b\\}\\{c,d\\}", EscapeString("{a,b}{c,d}", opts, nullptr));
 }
 
 TEST(Escape, NinjaPreformatted) {
   EscapeOptions opts;
   opts.mode = ESCAPE_NINJA_PREFORMATTED_COMMAND;
 
   // Only $ is escaped.
   EXPECT_EQ("a: \"$$\\b<;", EscapeString("a: \"$\\b<;", opts, nullptr));
 }