New build flag system, convert Google Now flag

chrome/chrome_features.gyp

Index: chrome/chrome_features.gyp
diff --git a/chrome/chrome_features.gyp b/chrome/chrome_features.gyp
new file mode 100644
index 0000000000000000000000000000000000000000..0d29f18f90a940e127ed01900f2dc1c6670b694f
--- /dev/null
+++ b/chrome/chrome_features.gyp
@@ -0,0 +1,22 @@
+# 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.
+
+{
+  'includes': [
+    'chrome_features.gypi',
+  ],
+  'targets': [
+    {
+      # GN version: //chrome/common:features
+      'target_name': 'chrome_common_features',
+      'includes': [ '../build/buildflag_header.gypi' ],
+      'variables': {
+        'buildflag_header_path': 'chrome/common/features.h',
+        'buildflag_flags': [
+          'ENABLE_GOOGLE_NOW=<(enable_google_now)',
+        ],
+      },
+    },
+  ]
+}