[Windows MSVC CFG] Add support for CFG, and enable on chrome.exe & chrome_elf.dll.

build/config/win/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/clang/clang.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/win/visual_studio_version.gni")
 import("//build/toolchain/toolchain.gni")
 
@@ skipping 246 matching lines @@
   }
 
   if (win_linker_timing) {
     ldflags += [
       "/time",
       "/verbose:incr",
     ]
   }
 }
 
+# Control Flow Guard (CFG)
+# https://msdn.microsoft.com/en-us/library/windows/desktop/mt637065.aspx
+config("win_msvc_cfg") {
+  # /DYNAMICBASE (ASLR) is turned off in debug builds, therefore CFG can’t be
+  # turned on either.
+  if (!is_clang && !is_debug) {
+    cflags = [ "/guard:cf" ]
+    ldflags = [ "/guard:cf" ]
+  }
+}
+
 # CRT --------------------------------------------------------------------------
 
 # Configures how the runtime library (CRT) is going to be used.
 # See https://msdn.microsoft.com/en-us/library/2kzt1wy3.aspx for a reference of
 # what each value does.
 config("default_crt") {
   if (is_component_build) {
     # Component mode: dynamic CRT. Since the library is shared, it requires
     # exceptions or will give errors about things not matching, so keep
     # exceptions on.
@@ skipping 130 matching lines @@
 
 # Internal stuff --------------------------------------------------------------
 
 # Config used by the MIDL template to disable warnings.
 config("midl_warnings") {
   if (is_clang) {
     # MIDL generates code like "#endif !_MIDL_USE_GUIDDEF_".
     cflags = [ "-Wno-extra-tokens" ]
   }
 }