Config changes to support target_os="fuchsia"

build/config/sysroot.gni

 # 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.
 
 # This header file defines the "sysroot" variable which is the absolute path
 # of the sysroot. If no sysroot applies, the variable will be an empty string.
 
 import("//build/config/chrome_build.gni")
 
 declare_args() {
@@ skipping 57 matching lines @@
                     [ rebase_path(sysroot) ],
                     "string") == "True",
         "Missing sysroot ($sysroot). To fix, run: build/linux/sysroot_scripts/install-sysroot.py --arch=$_script_arch")
   }
 } else if (is_mac) {
   import("//build/config/mac/mac_sdk.gni")
   sysroot = mac_sdk_path
 } else if (is_ios) {
   import("//build/config/ios/ios_sdk.gni")
   sysroot = ios_sdk_path
+} else if (is_fuchsia) {
+  import("//build/config/fuchsia/config.gni")
+  if (current_cpu == "arm64") {
+    sysroot = fuchsia_sdk + "/sysroot/aarch64-fuchsia"
+  } else if (current_cpu == "x64") {
+    sysroot = fuchsia_sdk + "/sysroot/x86_64-fuchsia"
+  } else {
+    sysroot = ""
+  }
+  sysroot_stamp = rebase_path("$sysroot/.stamp")
+  sysroot_version = read_file(sysroot_stamp, "trim string")
 } else {
   sysroot = ""
 }