New build flag system, convert Google Now flag

chrome/common/BUILD.gn

 # Copyright 2014 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.
 
+import("//build/buildflag_header.gni")
+import("//chrome/common/features.gni")
 import("//chrome/version.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//tools/grit/grit_rule.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
                           [ rebase_path("../chrome_common.gypi") ],
                           "scope",
                           [ "../chrome_common.gypi" ])
 
 # GYP version: chrome/chrome_resources.gyp:chrome_resources
@@ skipping 14 matching lines @@
   grit("extensions_api_resources") {
     source = "extensions_api_resources.grd"
     output_dir = "$root_gen_dir/chrome"
     outputs = [
       "grit/extensions_api_resources.h",
       "extensions_api_resources.pak",
     ]
   }
 }
 
+buildflag_header("features") {
+  header = "features.h"
+  flags = [ "ENABLE_GOOGLE_NOW=$enable_google_now" ]
+}
+
 # GYP version: chrome/chrome_common.gypi:common
 static_library("common") {
   sources = rebase_path(gypi_values.chrome_common_sources, ".", "//chrome")
   defines = []
 
   configs += [
     "//build/config:precompiled_headers",
     "//build/config/compiler:wexit_time_destructors",
   ]
 
   public_deps = [
+    ":features",
     "//base:base",
     "//base:base_static",
     "//base:i18n",
     "//base:prefs",
     "//chrome:resources",
     "//chrome:strings",
     "//chrome/app/theme:theme_resources",
     "//chrome/common:constants",
     "//chrome/common/safe_browsing:proto",
     "//chrome/common/variations:fieldtrial_testing_config",
@@ skipping 249 matching lines @@
     "pref_font_script_names-inl.h",
     "pref_font_webkit_names.h",
     "pref_names.cc",
     "pref_names.h",
   ]
 
   public_deps = [
     "//content/public/common:result_codes",
   ]
   deps = [
+    ":features",
     ":version_header",
     "//base",
     "//base/third_party/dynamic_annotations",
     "//components/bookmarks/common",
     "//third_party/widevine/cdm:version_h",
   ]
 
   if (enable_nacl) {
     deps += [ "//components/nacl:nacl_switches" ]
   }
@@ skipping 57 matching lines @@
     ":constants",
     "//base",
   ]
 }
 
 mojom("mojo_bindings") {
   sources = [
     "resource_usage_reporter.mojom",
   ]
 }