Remove the expat and jsoncpp to reduce the binary size.

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 350 matching lines @@
   if (is_win && is_clang) {
     cflags = [
       # Disable warnings failing when compiling with Clang on Windows.
       # https://bugs.chromium.org/p/webrtc/issues/detail?id=5366
       "-Wno-sign-compare",
       "-Wno-missing-braces",
     ]
   }
 }
 
+rtc_source_set("rtc_json") {
+  defines = []
+  sources = [
+    "json.cc",
+    "json.h",
+  ]
+  if (rtc_build_json) {
+    public_deps = [
+      "//third_party/jsoncpp",
+    ]
+  } else {
+    include_dirs = [ "$rtc_jsoncpp_root" ]
+
+    # When defined changes the include path for json.h to where it is
+    # expected to be when building json outside of the standalone build.
+    defines += [ "WEBRTC_EXTERNAL_JSON" ]
+  }
+}
+
 rtc_static_library("rtc_base") {
   cflags = []
   cflags_cc = []
   libs = []
   defines = []
   deps = [
     "..:webrtc_common",
   ]
   public_deps = [
     ":rtc_base_approved",
@@ skipping 115 matching lines @@
   if (build_with_chromium) {
     if (is_win) {
       sources += [ "../../webrtc_overrides/webrtc/base/win32socketinit.cc" ]
     }
     include_dirs = [ "../../boringssl/src/include" ]
     public_configs += [ ":rtc_base_chromium_config" ]
   } else {
     configs += [ ":rtc_base_warnings_config" ]
     sources += [
       "callback.h",
-      "json.cc",
-      "json.h",
       "logsinks.cc",
       "logsinks.h",
       "mathutils.h",
       "optionsfile.cc",
       "optionsfile.h",
       "rollingaccumulator.h",
       "sslroots.h",
       "testbase64.h",
       "testclient.cc",
       "testclient.h",
       "transformadapter.cc",
       "transformadapter.h",
       "virtualsocketserver.cc",
       "virtualsocketserver.h",
       "window.h",
     ]
 
     if (is_win) {
       sources += [
         "win32socketinit.cc",
         "win32socketinit.h",
         "win32socketserver.cc",
         "win32socketserver.h",
       ]
     }
-
-    if (rtc_build_json) {
-      deps += [ "//third_party/jsoncpp" ]
-    } else {
-      include_dirs = [ "$rtc_jsoncpp_root" ]
-
-      # When defined changes the include path for json.h to where it is
-      # expected to be when building json outside of the standalone build.
-      defines += [ "WEBRTC_EXTERNAL_JSON" ]
-    }
   }  # !build_with_chromium
 
   if (rtc_build_ssl) {
     deps += [ "//third_party/boringssl" ]
   } else {
     configs += [ ":external_ssl_library" ]
   }
 
   if (is_android) {
     sources += [
@@ skipping 380 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",
     ]
   }
 }