Revert of New build flag system, convert Google Now flag

build/buildflag.h

-// 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.
-
-#ifndef BUILD_BUILDFLAG_H_
-#define BUILD_BUILDFLAG_H_
-
-// These macros un-mangle the names of the build flags in a way that looks
-// natural, and gives errors if the flag is not defined. Normally in the
-// preprocessor it's easy to make mistakes that interpret "you haven't done
-// the setup to know what the flag is" as "flag is off". Normally you would
-// include the generated header rather than include this file directly.
-//
-// This is for use with generated headers. See build/build_header.gni.
-
-// This dance of two macros does a concatenation of two preprocessor args using
-// ## doubly indirectly because using ## directly prevents macros in that
-// parameter from being expanded.
-#define BUILDFLAG_CAT_INDIRECT(a, b) a ## b
-#define BUILDFLAG_CAT(a, b) BUILDFLAG_CAT_INDIRECT(a, b)
-
-// Accessor for build flags.
-//
-// To test for a value, if the build file specifies:
-//
-//   ENABLE_FOO=true
-//
-// Then you would check at build-time in source code with:
-//
-//   #include "foo_flags.h"  // The header the build file specified.
-//
-//   #if BUILDFLAG(ENABLE_FOO)
-//     ...
-//   #endif
-//
-// There will no #define called ENABLE_FOO so if you accidentally test for
-// whether that is defined, it will always be negative. You can also use
-// the value in expressions:
-//
-//   const char kSpamServerName[] = BUILDFLAG(SPAM_SERVER_NAME);
-//
-// Because the flag is accessed as a preprocessor macro with (), an error
-// will be thrown if the proper header defining the internal flag value has
-// not been included.
-#define BUILDFLAG(flag) (BUILDFLAG_CAT(BUILDFLAG_INTERNAL_, flag)())
-
-#endif  // BUILD_BUILDFLAG_H_