[MBI] Remove IPCTaskRunner usage on RenderThreadImpl

We are going to remove ipc_task_queue and ipc_task_runner. The scheduling policy of ipc_task_queue is the same as the default task queue. Nowadays, we are using per-frame task queues as much as possible. And if there are no relevant per-frame task queues, then we can use the (per-isolate) default task queues.

[related design doc section]
https://docs.google.com/document/d/1y-vHkrD1z2RtyWYwT6rJkSLHClYNjDDpUbTtBU7l95A/edit#bookmark=id.eeuir8g768ou

Bug: 1105403
Change-Id: I034961b5d320a3a43b93bcbeabbcb495e72a20e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2332089Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Tal Pressman <talp@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Commit-Queue: Minoru Chikamune <chikamune@chromium.org>
Cr-Commit-Position: refs/heads/master@{#794828}

content/renderer/render_thread_impl.cc

@@ -531,11 +531,12 @@ RenderThreadImpl::RenderThreadImpl(
     const InProcessChildThreadParams& params,
     int32_t client_id,
     std::unique_ptr<blink::scheduler::WebThreadScheduler> scheduler)
-    : ChildThreadImpl(base::DoNothing(),
+    : ChildThreadImpl(
+          base::DoNothing(),
           Options::Builder()
               .InBrowserProcess(params)
               .ConnectToBrowser(true)
-                          .IPCTaskRunner(scheduler->IPCTaskRunner())
+              .IPCTaskRunner(scheduler->DeprecatedDefaultTaskRunner())
               .ExposesInterfacesToBrowser()
               .Build()),
       main_thread_scheduler_(std::move(scheduler)),
@@ -561,10 +562,11 @@ int32_t GetClientIdFromCommandLine() {
 RenderThreadImpl::RenderThreadImpl(
     base::RepeatingClosure quit_closure,
     std::unique_ptr<blink::scheduler::WebThreadScheduler> scheduler)
-    : ChildThreadImpl(std::move(quit_closure),
+    : ChildThreadImpl(
+          std::move(quit_closure),
           Options::Builder()
               .ConnectToBrowser(true)
-                          .IPCTaskRunner(scheduler->IPCTaskRunner())
+              .IPCTaskRunner(scheduler->DeprecatedDefaultTaskRunner())
               .ExposesInterfacesToBrowser()
               .Build()),
       main_thread_scheduler_(std::move(scheduler)),
@@ -2181,8 +2183,9 @@ void RenderThreadImpl::OnSyncMemoryPressure(
 void RenderThreadImpl::OnRendererInterfaceReceiver(
     mojo::PendingAssociatedReceiver<mojom::Renderer> receiver) {
   DCHECK(!renderer_receiver_.is_bound());
-  renderer_receiver_.Bind(std::move(receiver),
-                          GetWebMainThreadScheduler()->IPCTaskRunner());
+  renderer_receiver_.Bind(
+      std::move(receiver),
+      GetWebMainThreadScheduler()->DeprecatedDefaultTaskRunner());
 }
 
 bool RenderThreadImpl::NeedsToRecordFirstActivePaint(

third_party/blink/public/platform/scheduler/test/web_mock_thread_scheduler.h

@@ -27,6 +27,8 @@ class WebMockThreadScheduler : public WebThreadScheduler {
 
   MOCK_METHOD0(DefaultTaskRunner,
                scoped_refptr<base::SingleThreadTaskRunner>());
+  MOCK_METHOD0(DeprecatedDefaultTaskRunner,
+               scoped_refptr<base::SingleThreadTaskRunner>());
   MOCK_METHOD0(CompositorTaskRunner,
                scoped_refptr<base::SingleThreadTaskRunner>());
   MOCK_METHOD0(InputTaskRunner, scoped_refptr<base::SingleThreadTaskRunner>());