Fix all -Wnon-virtual-dtor warnings.

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 10 matching lines @@
 config("rtc_base_config") {
   include_dirs = [
     "//third_party/jsoncpp/overrides/include",
     "//third_party/jsoncpp/source/include",
   ]
 
   defines = [
     "FEATURE_ENABLE_SSL",
     "LOGGING=1",
   ]
-
-  if (is_posix) {
-    # TODO(henrike): issue 3307, make rtc_base build without disabling
-    # these flags.
-    cflags_cc = [ "-Wno-non-virtual-dtor" ]
-  }
 }
 
 config("rtc_base_chromium_config") {
   defines = [ "NO_MAIN_THREAD_WRAPPING" ]
 }
 
 config("openssl_config") {
   defines = [
     "SSL_USE_OPENSSL",
     "HAVE_OPENSSL_SSL_H",
@@ skipping 416 matching lines @@
       defines += [ "WEBRTC_EXTERNAL_JSON" ]
     }
   }  # !build_with_chromium
 
   # TODO(henrike): issue 3307, make rtc_base build with the Chromium default
   # compiler settings.
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   if (!is_win) {
     cflags += [ "-Wno-uninitialized" ]
-    cflags_cc += [ "-Wno-non-virtual-dtor" ]
   }
 
   if (rtc_build_ssl) {
     deps += [ "//third_party/boringssl" ]
   } else {
     configs += [ "external_ssl_library" ]
   }
 
   if (is_android) {
     sources += [
@@ skipping 111 matching lines @@
     defines += [ "timezone=_timezone" ]
     sources -= [ "ifaddrs_converter.cc" ]
   }
 }
 
 source_set("gtest_prod") {
   sources = [
     "gtest_prod_util.h",
   ]
 }