Delete AsyncSocket class, merge into Socket class

Bug: webrtc:13065
Change-Id: I13afee2386ea9c4de0e4fa95133f0c4d3ec826e8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227031
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34787}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 40c4835..90bb8b7 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -737,7 +737,6 @@
     "null_socket_server.h",
   ]
   deps = [
-    ":async_socket",
     ":checks",
     ":rtc_event",
     ":socket",
@@ -818,10 +817,7 @@
 
 rtc_source_set("socket_factory") {
   sources = [ "socket_factory.h" ]
-  deps = [
-    ":async_socket",
-    ":socket",
-  ]
+  deps = [ ":socket" ]
 }
 
 rtc_library("async_socket") {
@@ -846,7 +842,9 @@
   deps = [
     ":macromagic",
     ":socket_address",
+    "third_party/sigslot",
   ]
+  absl_deps = [ "//third_party/abseil-cpp/absl/base:core_headers" ]
   if (is_win) {
     deps += [ ":win32" ]
   }
@@ -1294,7 +1292,6 @@
         "socket_unittest.h",
       ]
       deps = [
-        ":async_socket",
         ":checks",
         ":gunit_helpers",
         ":ip_address",
@@ -1369,7 +1366,6 @@
         sources += [ "win/windows_version_unittest.cc" ]
       }
       deps = [
-        ":async_socket",
         ":bounded_inline_vector",
         ":checks",
         ":criticalsection",
@@ -1505,13 +1501,13 @@
         "unique_id_generator_unittest.cc",
       ]
       deps = [
-        ":async_socket",
         ":checks",
         ":gunit_helpers",
         ":ip_address",
         ":net_helpers",
         ":null_socket_server",
         ":rtc_base_tests_utils",
+        ":socket",
         ":socket_address",
         ":socket_factory",
         ":socket_server",