Delete reference to webrtc_overides/rtc_base/task_queue.cc.

This change depends on Chromium cl
https://chromium-review.googlesource.com/c/chromium/src/+/681814,
which must be landed first.

Bug: webrtc:8166
Change-Id: I8e1c96ad5927e1d9d4e45e6f6c0b5f712d58cef7
Reviewed-on: https://webrtc-review.googlesource.com/3940
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20071}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 93f8990..cf6ff94 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -345,32 +345,26 @@
     ":rtc_base_approved",
     ":rtc_task_queue_api",
   ]
-  if (build_with_chromium) {
+  if (rtc_build_libevent) {
+    deps += [ "//base/third_party/libevent" ]
+  }
+  if (rtc_enable_libevent) {
     sources = [
-      "../../webrtc_overrides/rtc_base/task_queue.cc",
+      "task_queue_libevent.cc",
+      "task_queue_posix.cc",
+      "task_queue_posix.h",
     ]
   } else {
-    if (rtc_build_libevent) {
-      deps += [ "//base/third_party/libevent" ]
-    }
-    if (rtc_enable_libevent) {
+    if (is_mac || is_ios) {
       sources = [
-        "task_queue_libevent.cc",
+        "task_queue_gcd.cc",
         "task_queue_posix.cc",
-        "task_queue_posix.h",
       ]
-    } else {
-      if (is_mac || is_ios) {
-        sources = [
-          "task_queue_gcd.cc",
-          "task_queue_posix.cc",
-        ]
-      }
-      if (is_win) {
-        sources = [
-          "task_queue_win.cc",
-        ]
-      }
+    }
+    if (is_win) {
+      sources = [
+        "task_queue_win.cc",
+      ]
     }
   }
 }