Poison default task queue factory

Users of webrtc generally should be able to choose own task queue implementation.
Poison avoids accidental dependency of a low level component on the default implementation
Android and ios apis are still de-facto forced to use the default implementation.

Bug: webrtc:10284
Change-Id: I67ecf2317f43ee32b0c9e8a6e69f1e0987cf1914
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/144786
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28524}

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
index 8334573..af0de9f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -675,3 +675,6 @@
 
 group("poison_software_video_codecs") {
 }
+
+group("poison_default_task_queue") {
+}

api/BUILD.gn

diff --git a/api/BUILD.gn b/api/BUILD.gn
index 01d79ea..645daee 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -38,6 +38,7 @@
 if (!build_with_chromium) {
   rtc_static_library("create_peerconnection_factory") {
     visibility = [ "*" ]
+    allow_poison = [ "default_task_queue" ]
     sources = [
       "create_peerconnection_factory.cc",
       "create_peerconnection_factory.h",

api/task_queue/BUILD.gn

diff --git a/api/task_queue/BUILD.gn b/api/task_queue/BUILD.gn
index 19b9e0e..4b84607 100644
--- a/api/task_queue/BUILD.gn
+++ b/api/task_queue/BUILD.gn
@@ -49,6 +49,9 @@
 
 rtc_source_set("default_task_queue_factory") {
   visibility = [ "*" ]
+  if (!is_ios && !is_android) {
+    poisonous = [ "default_task_queue" ]
+  }
   sources = [
     "default_task_queue_factory.h",
   ]

media/BUILD.gn

diff --git a/media/BUILD.gn b/media/BUILD.gn
index 6361fb8..bf585ac 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -343,6 +343,7 @@
   visibility = [ "*" ]
   allow_poison = [
     "audio_codecs",
+    "default_task_queue",
     "software_video_codecs",
   ]
   sources = [

sdk/BUILD.gn

diff --git a/sdk/BUILD.gn b/sdk/BUILD.gn
index 2eab502..8303d8a 100644
--- a/sdk/BUILD.gn
+++ b/sdk/BUILD.gn
@@ -459,7 +459,10 @@
     if (rtc_use_metal_rendering) {
       rtc_static_library("metal_objc") {
         visibility = [ "*" ]
-        allow_poison = [ "audio_codecs" ]  # TODO(bugs.webrtc.org/8396): Remove.
+        allow_poison = [
+          "audio_codecs",  # TODO(bugs.webrtc.org/8396): Remove.
+          "default_task_queue",
+        ]
         sources = [
           "objc/components/renderer/metal/RTCMTLI420Renderer.h",
           "objc/components/renderer/metal/RTCMTLI420Renderer.mm",
@@ -658,7 +661,10 @@
     # The applications which only use WebRTC DataChannel can depend on this.
     rtc_static_library("peerconnectionfactory_no_media_objc") {
       visibility = [ "*" ]
-      allow_poison = [ "audio_codecs" ]  # TODO(bugs.webrtc.org/8396): Remove.
+      allow_poison = [
+        "audio_codecs",  # TODO(bugs.webrtc.org/8396): Remove.
+        "default_task_queue",
+      ]
       defines = [ "HAVE_NO_MEDIA" ]
 
       sources = [
@@ -776,7 +782,10 @@
 
     rtc_static_library("peerconnectionfactory_base_objc") {
       visibility = [ "*" ]
-      allow_poison = [ "audio_codecs" ]  # TODO(bugs.webrtc.org/8396): Remove.
+      allow_poison = [
+        "audio_codecs",  # TODO(bugs.webrtc.org/8396): Remove.
+        "default_task_queue",
+      ]
       configs += [
         "..:no_exit_time_destructors",
         "..:no_global_constructors",
@@ -908,7 +917,6 @@
         ":videorendereradapter_objc",
         ":videosource_objc",
         ":videotoolbox_objc",
-        "../api:create_peerconnection_factory",
         "../api:libjingle_peerconnection_api",
         "../api:rtc_event_log_output_file",
         "../api:rtc_stats_api",

webrtc.gni

diff --git a/webrtc.gni b/webrtc.gni
index 9e13283..e27a84a 100644
--- a/webrtc.gni
+++ b/webrtc.gni
@@ -368,6 +368,9 @@
 
   # Software video codecs (VP8 and VP9 through libvpx).
   "software_video_codecs",
+
+  # Default task queue implementation.
+  "default_task_queue",
 ]
 
 absl_include_config = "//third_party/abseil-cpp:absl_include_config"