Reland of Decoupling rtc_base from Obj-C code

webrtc/rtc_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 411 matching lines @@
     ]
   } 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") {
+rtc_source_set("rtc_base") {
+  public_deps = [
+    ":rtc_base_generic",
+  ]
+  if (is_ios || is_mac) {
+    public_deps += [ ":rtc_base_objc" ]
+  }
+}
+
+if (is_ios || is_mac) {
+  rtc_source_set("rtc_base_objc") {
+    sources = [
+      "thread_darwin.mm",
+    ]
+    deps = [
+      ":rtc_base_generic",
+    ]
+    visibility = [ ":rtc_base" ]
+  }
+}
+
+rtc_source_set("rtc_base_generic") {
   cflags = []
   cflags_cc = []
   libs = []
   defines = []
   deps = [
     "..:webrtc_common",
   ]
   public_deps = [
     ":rtc_base_approved",
   ]
@@ skipping 88 matching lines @@
     "sslidentity.cc",
     "sslidentity.h",
     "sslstreamadapter.cc",
     "sslstreamadapter.h",
     "stream.cc",
     "stream.h",
     "thread.cc",
     "thread.h",
   ]
 
+  visibility = [
+    ":rtc_base",
+    ":rtc_base_objc",
+  ]
+
   # TODO(henrike): issue 3307, make rtc_base build with the Chromium default
   # compiler settings.
   suppressed_configs += [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   if (!is_win) {
     cflags += [ "-Wno-uninitialized" ]
   }
 
   if (build_with_chromium) {
     if (is_win) {
@@ skipping 39 matching lines @@
       "ifaddrs-android.h",
     ]
 
     libs += [
       "log",
       "GLESv2",
     ]
   }
 
   if (is_ios || is_mac) {
-    sources += [
-      "macifaddrs_converter.cc",
-      "thread_darwin.mm",
-    ]
+    sources += [ "macifaddrs_converter.cc" ]
   }
 
   if (use_x11) {
     libs += [
       "dl",
       "rt",
       "Xext",
       "X11",
       "Xcomposite",
       "Xrender",
@@ skipping 460 matching lines @@
       "java/src/org/webrtc/ContextUtils.java",
       "java/src/org/webrtc/Logging.java",
       "java/src/org/webrtc/Size.java",
       "java/src/org/webrtc/ThreadUtils.java",
     ]
 
     # TODO(sakal): Fix build hooks crbug.com/webrtc/8148
     no_build_hooks = true
   }
 }