GN: Allow users to enable DCHECK on Release builds.

build/config/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/allocator.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/module_args/v8.gni")
 
 declare_args() {
   # When set, turns off the (normally-on) iterator debugging and related stuff
   # that is normally turned on for Debug builds. These are generally useful for
   # catching bugs but in some cases may cause conflicts or excessive slowness.
   disable_iterator_debugging = false
 
   # Set to true to not store any build metadata (this isn't working yet but
   # this flag will help us to get there). See http://crbug.com/314403.
   # TODO(sebmarchand): Update this comment once this flag guarantee that
   #     there's no build metadata in the build artifacts.
   dont_embed_build_metadata = false
+
+  # Set to true to enable dcheck in Release builds.
+  dcheck_always_on = false
 }
 
 # TODO(brettw) Most of these should be removed. Instead of global feature
 # flags, we should have more modular flags that apply only to a target and its
 # dependents. For example, depending on the "x11" meta-target should define
 # USE_X11 for all dependents so that everything that could use X11 gets the
 # define, but anything that doesn't depend on X11 doesn't see it.
 #
 # For now we define these globally to match the current GYP build.
 config("feature_flags") {
@@ skipping 35 matching lines @@
       # Can be defined without ENABLE_BASIC_PRINTING.
       defines += [ "ENABLE_PRINT_PREVIEW=1" ]
     }
   }
   if (enable_spellcheck) {
     defines += [ "ENABLE_SPELLCHECK=1" ]
   }
   if (dont_embed_build_metadata) {
     defines += [ "DONT_EMBED_BUILD_METADATA" ]
   }
+  if (dcheck_always_on) {
+    defines += [ "DCHECK_ALWAYS_ON=1" ]
+  }
   if (use_udev) {
     # TODO(brettw) should probably be "=1".
     defines += [ "USE_UDEV" ]
   }
   if (toolkit_views) {
     defines += [ "TOOLKIT_VIEWS=1" ]
   }
   if (ui_compositor_image_transport) {
     # TODO(brettw) should probably be "=1".
     defines += [ "UI_COMPOSITOR_IMAGE_TRANSPORT" ]
@@ skipping 217 matching lines @@
       "CoreFoundation.framework",
       "CoreGraphics.framework",
       "CoreText.framework",
       "Foundation.framework",
       "UIKit.framework",
     ]
   } else if (is_linux) {
     libs = [ "dl" ]
   }
 }