Delete or update left-over ASSERT use and comments.

webrtc/base/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/crypto.gni")
 import("//build/config/ui.gni")
@@ skipping 647 matching lines @@
     defines += [ "_CRT_NONSTDC_NO_DEPRECATE" ]
   }
 
   if (is_posix) {
     sources += [
       "ifaddrs_converter.cc",
       "ifaddrs_converter.h",
       "unixfilesystem.cc",
       "unixfilesystem.h",
     ]
-    if (is_debug) {
-      # The Chromium build/common.gypi defines this for all posix
-      # _except_ for ios & mac.  We want it there as well, e.g.
-      # because ASSERT and friends trigger off of it.
-      defines += [ "_DEBUG" ]
-    }

[kwiberg-webrtc, 2017/01/23 12:25:14]

Curiously, _DEBUG seems to be a Windows thing, not a posix thing as implied by
this code: http://stackoverflow.com/questions/2290509/debug-vs-ndebug

I'm not sure if we need it or not. Did we use it before? E.g. was ASSERT defined
in terms of _DEBUG as the comment claims?

[nisse-webrtc, 2017/01/23 12:53:03]

I've search history, _DEBUG was used in lots of places before cl
https://codereview.webrtc.org/1429513004 (but not for ASSERT, as far as I see).
More recently, it was used in peerconnection_unittests.cc, and that use deleted
in cl https://codereview.webrtc.org/1837393002

   }
 
   if (is_nacl) {
     deps += [ "//native_client_sdk/src/libraries/nacl_io" ]
     defines += [ "timezone=_timezone" ]
     sources -= [ "ifaddrs_converter.cc" ]
   }
   if (is_win && is_clang) {
     # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
     suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
@@ skipping 260 matching lines @@
 
 if (is_android) {
   android_library("base_java") {
     java_files = [
       "java/src/org/webrtc/Logging.java",
       "java/src/org/webrtc/Size.java",
       "java/src/org/webrtc/ThreadUtils.java",
     ]
   }
 }