[Merge-102] Make metro TQ use the same base::TaskTraits as non-metro TQ.

I didn't think the task traits made much of a difference and forgot to
have them align, but when seeing an increase of existing crashes in
https://crbug.com/1319036, I'm wondering if the traits could affect
which thread is chosen during block-invokes.

Whether or not it makes a difference, having the traits match makes
sense since there was no intent to change the behavior of the original
TQ with regards to traits.

(cherry picked from commit 4c01b57)

Bug: 1319786, 1319036
Change-Id: Iaef1ad9860dc89cd2fe59f67448f7f11eaa15934
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3607671
Reviewed-by: Markus Handell <handellm@google.com>
Commit-Queue: Henrik Boström <hbos@chromium.org>
Auto-Submit: Henrik Boström <hbos@chromium.org>
Reviewed-by: Mirko Bonadei <mbonadei@chromium.org>
Commit-Queue: Mirko Bonadei <mbonadei@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#996080}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3610089
Cr-Commit-Position: refs/branch-heads/5005@{#193}
Cr-Branched-From: 5b4d945-refs/heads/main@{#992738}

third_party/webrtc_overrides/metronome_task_queue_factory.cc

@@ -17,6 +17,7 @@
 #include "third_party/webrtc/api/task_queue/task_queue_factory.h"
 #include "third_party/webrtc_overrides/coalesced_tasks.h"
 #include "third_party/webrtc_overrides/metronome_source.h"
+#include "third_party/webrtc_overrides/task_queue_factory.h"
 
 namespace blink {
 
@@ -25,7 +26,7 @@ const base::Feature kWebRtcMetronomeTaskQueue{
 
 class WebRtcMetronomeTaskQueue : public webrtc::TaskQueueBase {
  public:
-  WebRtcMetronomeTaskQueue();
+  explicit WebRtcMetronomeTaskQueue(base::TaskTraits traits);
 
   // webrtc::TaskQueueBase implementation.
   void Delete() override;
@@ -56,8 +57,9 @@ class WebRtcMetronomeTaskQueue : public webrtc::TaskQueueBase {
   CoalescedTasks coalesced_tasks_;
 };
 
-WebRtcMetronomeTaskQueue::WebRtcMetronomeTaskQueue()
-    : task_runner_(base::ThreadPool::CreateSequencedTaskRunner({})),
+WebRtcMetronomeTaskQueue::WebRtcMetronomeTaskQueue(base::TaskTraits traits)
+    : task_runner_(
+          base::ThreadPool::CreateSequencedTaskRunner(std::move(traits))),
       is_active_(new base::RefCountedData<bool>(true)) {}
 
 void Deactivate(scoped_refptr<base::RefCountedData<bool>> is_active,
@@ -157,7 +159,7 @@ class WebrtcMetronomeTaskQueueFactory final : public webrtc::TaskQueueFactory {
   std::unique_ptr<webrtc::TaskQueueBase, webrtc::TaskQueueDeleter>
   CreateTaskQueue(absl::string_view name, Priority priority) const override {
     return std::unique_ptr<webrtc::TaskQueueBase, webrtc::TaskQueueDeleter>(
-        new WebRtcMetronomeTaskQueue());
+        new WebRtcMetronomeTaskQueue(TaskQueuePriority2Traits(priority)));
   }
 };
 

third_party/webrtc_overrides/task_queue_factory.cc

@@ -92,8 +92,6 @@ void WebrtcTaskQueue::PostDelayedTask(std::unique_ptr<webrtc::QueuedTask> task,
       base::subtle::DelayPolicy::kPrecise);
 }
 
-namespace {
-
 base::TaskTraits TaskQueuePriority2Traits(
     webrtc::TaskQueueFactory::Priority priority) {
   // The content/renderer/media/webrtc/rtc_video_encoder.* code
@@ -119,6 +117,8 @@ base::TaskTraits TaskQueuePriority2Traits(
   }
 }
 
+namespace {
+
 class WebrtcTaskQueueFactory final : public webrtc::TaskQueueFactory {
  public:
   WebrtcTaskQueueFactory() = default;

third_party/webrtc_overrides/task_queue_factory.h

@@ -12,6 +12,13 @@
 #include "third_party/webrtc/api/task_queue/task_queue_factory.h"
 #include "third_party/webrtc/rtc_base/system/rtc_export.h"
 
+namespace blink {
+
+RTC_EXPORT base::TaskTraits TaskQueuePriority2Traits(
+    webrtc::TaskQueueFactory::Priority priority);
+
+}  // namespace blink
+
 // Creates factory for webrtc::TaskQueueBase backed by base::SequencedTaskRunner
 // Tested by
 // /third_party/blink/renderer/platform/peerconnection/task_queue_factory_test.cc