Enable -Wdeprecated-register in CrOS builds.

build/config/compiler/BUILD.gn

 # 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.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
@@ skipping 1055 matching lines @@
 
       # TODO(thakis): This used to be implied by -Wno-unused-function,
       # which we no longer use. Check if it makes sense to remove
       # this as well. http://crbug.com/316352
       "-Wno-unneeded-internal-declaration",
 
       # TODO(hans): Get this cleaned up, http://crbug.com/428099
       "-Wno-inconsistent-missing-override",
     ]
 
-    if (is_chromeos || (is_linux && target_cpu == "x86")) {
+    if (is_linux && target_cpu == "x86") {
       cflags += [
-        # TODO(thakis): Figure out why CrOS needs this, fix, remove.
-        # https://crbug.com/806812
         # TODO(thakis): Remove from 32-bit Linux eventually, https://707084
         "-Wno-deprecated-register",
       ]
     }
 
     # use_xcode_clang only refers to the iOS toolchain, host binaries use
     # chromium's clang always.
     if (!is_nacl && (!use_xcode_clang || current_toolchain == host_toolchain)) {
       # Flags NaCl (Clang 3.7) and Xcode 7.3 (Clang clang-703.0.31) do not
       # recognize.
@@ skipping 623 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }