Stop exposing libjingle_xmpp:rtc_task_runner from webrtc_overrides.

There is no reason to depend on libjingle_xmpp:rtc_task_runner from
//third_party/webrtc_overrides.

It was causing symbol visibility errors in the WebRTC component build
and after looking more carefully into it, it seems that WebRTC doesn't
need it, it is used in //jingle so this CL moves the dependency where
it is needed.

Bug: 896154
Change-Id: Icf24838a7b6220d5cabce1878b128caa3fe2fc9e
Reviewed-on: https://chromium-review.googlesource.com/c/1297359
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Henrik Grunell <grunell@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602433}

jingle/BUILD.gn

@@ -28,6 +28,7 @@ static_library("jingle_glue") {
     "//base/third_party/dynamic_annotations",
     "//net",
     "//services/network:network_service",
+    "//third_party/libjingle_xmpp:rtc_task_runner",
   ]
 
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
@@ -117,6 +118,7 @@ static_library("notifier") {
     "//net",
     "//third_party/expat",
     "//url",
+    "//third_party/libjingle_xmpp:rtc_task_runner",
   ]
 }
 
@@ -200,5 +202,6 @@ test("jingle_unittests") {
     "//services/network:test_support",
     "//testing/gmock",
     "//testing/gtest",
+    "//third_party/libjingle_xmpp:rtc_task_runner",
   ]
 }

third_party/webrtc_overrides/BUILD.gn

@@ -33,7 +33,6 @@ source_set("webrtc") {
     # TODO(kjellander): Start cleaning up this target as soon as
     # https://codereview.chromium.org/2022833002/ is landed. The target should
     # be removed entirely if possible.
-    "//third_party/libjingle_xmpp:rtc_task_runner",
     "//third_party/webrtc/rtc_base:rtc_base_approved",
   ]
   deps = [