[iOS] Disable NSAssert and GTMDevAssert 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/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/dcheck_always_on.gni")
 import("//build/config/features.gni")
@@ skipping 203 matching lines @@
       "WTF_USE_DYNAMIC_ANNOTATIONS=1",
     ]
   } else {
     defines += [ "NVALGRIND" ]
     if (!is_nacl) {
       # NaCl always enables dynamic annotations. Currently this value is set to
       # 1 for all .nexes.
       defines += [ "DYNAMIC_ANNOTATIONS_ENABLED=0" ]
     }
   }
+
+  if (is_ios) {
+    defines += [ "NS_BLOCK_ASSERTIONS=1" ]

[brettw, 2017/01/17 20:51:50]

Can you add a comment here about what this does and why we want it? (i.e. not
"because the GYP build had it").

[bzanotti, 2017/01/18 14:01:27]

Done.

+  }
 }
 
 # Default libraries ------------------------------------------------------------
 
 # This config defines the default libraries applied to all targets.
 config("default_libs") {
   if (is_win) {
     # TODO(brettw) this list of defaults should probably be smaller, and
     # instead the targets that use the less common ones (e.g. wininet or
     # winspool) should include those explicitly.
@@ skipping 159 matching lines @@
       #
       # TODO(sof): determine VS2015 status and retire the setting from all
       # precompiled configurations.
       cflags_c = [ "/wd4206" ]
     } else if (is_mac) {
       precompiled_header = "build/precompile.h"
       precompiled_source = "//build/precompile.h"
     }
   }
 }