[iOS] ios/web no longer depends on content::BrowserThread.

ios/web/web_thread_impl.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IOS_WEB_WEB_THREAD_IMPL_H_
 #define IOS_WEB_WEB_THREAD_IMPL_H_
 
 #include "base/threading/thread.h"
 #include "ios/web/public/web_thread.h"
 
 namespace web {
 
-class WebThreadDelegate;
+class WebTestSuiteListener;
 
 class WebThreadImpl : public WebThread, public base::Thread {
  public:
   // Construct a WebThreadImpl with the supplied identifier.  It is an error
   // to construct a WebThreadImpl that already exists.
   explicit WebThreadImpl(WebThread::ID identifier);
 
   // Special constructor for the main (UI) thread and unittests. If a
   // |message_loop| is provied, we use a dummy thread here since the main
   // thread already exists.
   WebThreadImpl(WebThread::ID identifier, base::MessageLoop* message_loop);
   ~WebThreadImpl() override;
 
   static void ShutdownThreadPool();
 
-  // TODO(stuartmorgan): Move this to WebThread (where it belongs) once
-  // the alternate BrowserThread-backed-WebThread implementation goes away. See
-  // the note in web_thread_delegate.h.
-  //
-  // Sets the delegate for the specified WebThread.
-  //
-  // Only one delegate may be registered at a time. Delegates may be
-  // unregistered by providing a nullptr pointer.
-  //
-  // If the caller unregisters a delegate before CleanUp has been
-  // called, it must perform its own locking to ensure the delegate is
-  // not deleted while unregistering.
-  static void SetDelegate(ID identifier, WebThreadDelegate* delegate);
-
  protected:
   void Init() override;
   void Run(base::MessageLoop* message_loop) override;
   void CleanUp() override;
 
  private:
   // This class implements all the functionality of the public WebThread
   // functions, but state is stored in the WebThreadImpl to keep
   // the API cleaner. Therefore make WebThread a friend class.
   friend class WebThread;
@@ skipping 16 matching lines @@
   // Common initialization code for the constructors.
   void Initialize();
 
   // Performs cleanup that needs to happen on the IO thread before calling the
   // embedder's CleanUp function.
   void IOThreadPreCleanUp();
 
   // For testing.
   friend class TestWebThreadBundle;
   friend class TestWebThreadBundleImpl;
+  friend class WebTestSuiteListener;
   static void FlushThreadPoolHelperForTesting();
 
   // The identifier of this thread.  Only one thread can exist with a given
   // identifier at a given time.
   ID identifier_;
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_WEB_THREAD_IMPL_H_