fuchsia: Use new, qualified error names, disable old names.

build/config/fuchsia/BUILD.gn

 # Copyright 2017 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/config/fuchsia/config.gni")
 import("//build/config/sysroot.gni")
 
 assert(is_fuchsia)
 assert(is_posix)
 
 config("compiler") {
-  defines = [ "SYSROOT_VERSION=$sysroot_version" ]
+  defines = [
+    # To force full builds after sysroot updates.
+    "SYSROOT_VERSION=$sysroot_version",
+
+    # Don't have include error codes that aren't prefixed with MX_ in
+    # magenta/errors.h, for they collide with ERR_ defines in chrome code.
+    "USE_MX_ERRORS",
+  ]
   cflags = []
   ldflags = []
   if (current_cpu == "arm64") {
     cflags += [ "--target=aarch64-fuchsia" ]
     ldflags += [ "--target=aarch64-fuchsia" ]
   } else if (current_cpu == "x64") {
     cflags += [ "--target=x86_64-fuchsia" ]
     ldflags += [ "--target=x86_64-fuchsia" ]
   } else {
     assert(false, "Unsupported architecture")
@@ skipping 16 matching lines @@
     # will be available. Raise to 8M which matches e.g. macOS.
     "-Wl,-z,stack-size=0x800000",
   ]
 
   libs = [
     "mxio",
     "magenta",
     "unwind",
   ]
 }