[scheduler] Remove webthread_impl_for_worker_scheduler from public API.

third_party/WebKit/public/platform/scheduler/child/webthread_base.h

Index: third_party/WebKit/public/platform/scheduler/child/webthread_base.h
diff --git a/third_party/WebKit/public/platform/scheduler/child/webthread_base.h b/third_party/WebKit/public/platform/scheduler/child/webthread_base.h
index a1d40bff298425a75acf65652f3ce3218aee0f7f..c000b31b74071aa12c6a18462f9f1d996924f215 100644
--- a/third_party/WebKit/public/platform/scheduler/child/webthread_base.h
+++ b/third_party/WebKit/public/platform/scheduler/child/webthread_base.h
@@ -22,6 +22,12 @@ class BLINK_PLATFORM_EXPORT WebThreadBase : public WebThread {
  public:
   ~WebThreadBase() override;
 
+  static std::unique_ptr<WebThreadBase> CreateWorkerThread(

[Sami, 2017/04/11 10:03:10]

Could we put these in WebThread instead and make WebThreadBase non-public? It's
really just meant to be a common base class for the different thread types
instead something that content/ should depend on.

[altimin, 2017/04/11 10:44:35]

There's a problem with WebThreadBase::Init method. I'll try to get rid of it,
but let's make one step at a time. I heard you liked small patches.

[Sami, 2017/04/11 11:46:28]

I don't believe I was told anything I say can be used against me :) But fair
enough, mind leaving a TODO at the top of this class?

+      const char* name,
+      base::Thread::Options options);
+  static std::unique_ptr<WebThreadBase> CreateCompositorThread(
+      base::Thread::Options options);
+
   // WebThread implementation.
   bool IsCurrentThread() const override;
   PlatformThreadId ThreadId() const override = 0;
@@ -43,6 +49,8 @@ class BLINK_PLATFORM_EXPORT WebThreadBase : public WebThread {
   // this thread. Can be called from any thread.
   virtual scheduler::SingleThreadIdleTaskRunner* GetIdleTaskRunner() const = 0;
 
+  virtual void Init() = 0;
+
  protected:
   class TaskObserverAdapter;