Revert of Remove all reference to carbon api

webrtc/base/BUILD.gn

Index: webrtc/base/BUILD.gn
diff --git a/webrtc/base/BUILD.gn b/webrtc/base/BUILD.gn
index 48f04e7281c3b5ea12ab356970fcb26a5620b48e..e166a4f7ba3f45274d33fd8e89b099196df1dc3e 100644
--- a/webrtc/base/BUILD.gn
+++ b/webrtc/base/BUILD.gn
@@ -65,6 +65,9 @@
       "Security.framework",
       "SystemConfiguration.framework",
     ]
+    if (current_cpu == "x86") {
+      libs += [ "Carbon.framework" ]
+    }
   }
 }
 
@@ -281,7 +284,6 @@
   defines = [ "LOGGING=1" ]
 
   sources = [
-    "applefilesystem.mm",
     "arraysize.h",
     "asyncfile.cc",
     "asyncfile.h",
@@ -330,6 +332,7 @@
     "httpcommon.h",
     "httprequest.cc",
     "httprequest.h",
+    "iosfilesystem.mm",
     "ipaddress.cc",
     "ipaddress.h",
     "linked_ptr.h",
@@ -659,6 +662,10 @@
     }
   }
 
+  if (is_ios || (is_mac && current_cpu != "x86")) {
+    defines += [ "CARBON_DEPRECATED=YES" ]
+  }
+
   if (is_linux || is_android) {
     sources += [
       "linux.cc",