[scheduler] Remove webthread_impl_for_worker_scheduler from public API.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index d1c054fd660fba30207b8fbc506ef4c871792628..6c478d38a81d4348994fe085ac90c5ea0902f634 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -156,7 +156,7 @@
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/platform/WebThread.h"
 #include "third_party/WebKit/public/platform/scheduler/child/compositor_worker_scheduler.h"
-#include "third_party/WebKit/public/platform/scheduler/child/webthread_impl_for_worker_scheduler.h"
+#include "third_party/WebKit/public/platform/scheduler/child/webthread_base.h"
 #include "third_party/WebKit/public/platform/scheduler/renderer/renderer_scheduler.h"
 #include "third_party/WebKit/public/web/WebDatabase.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
@@ -226,7 +226,6 @@ using blink::WebScriptController;
 using blink::WebSecurityPolicy;
 using blink::WebString;
 using blink::WebView;
-using blink::scheduler::WebThreadImplForWorkerScheduler;
 
 namespace content {
 
@@ -290,25 +289,6 @@ static_assert(
         blink::kWebMemoryPressureLevelCritical,
     "blink::WebMemoryPressureLevelCritical not align");
 
-class WebThreadForCompositor : public WebThreadImplForWorkerScheduler {
- public:
-  explicit WebThreadForCompositor(base::Thread::Options options)
-      : WebThreadImplForWorkerScheduler("Compositor", options) {
-    Init();
-  }
-  ~WebThreadForCompositor() override {}
-
- private:
-  // WebThreadImplForWorkerScheduler:
-  std::unique_ptr<blink::scheduler::WorkerScheduler> CreateWorkerScheduler()
-      override {
-    return base::MakeUnique<blink::scheduler::CompositorWorkerScheduler>(
-        GetThread());
-  }
-
-  DISALLOW_COPY_AND_ASSIGN(WebThreadForCompositor);
-};
-
 void* CreateHistogram(
     const char *name, int min, int max, size_t buckets) {
   if (min <= 0)
@@ -1087,7 +1067,8 @@ void RenderThreadImpl::InitializeCompositorThread() {
 #if defined(OS_ANDROID)
   options.priority = base::ThreadPriority::DISPLAY;
 #endif
-  compositor_thread_.reset(new WebThreadForCompositor(options));
+  compositor_thread_ =
+      blink::scheduler::WebThreadBase::CreateCompositorThread(options);
   blink_platform_impl_->SetCompositorThread(compositor_thread_.get());
   compositor_task_runner_ = compositor_thread_->GetTaskRunner();
   compositor_task_runner_->PostTask(