Cleanup by removing thread hop resource throttle code; experiment's over.

chrome/browser/renderer_host/thread_hop_resource_throttle.h

-// Copyright 2015 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 CHROME_BROWSER_RENDERER_HOST_THREAD_HOP_RESOURCE_THROTTLE_H_
-#define CHROME_BROWSER_RENDERER_HOST_THREAD_HOP_RESOURCE_THROTTLE_H_
-
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-#include "content/public/browser/resource_throttle.h"
-
-namespace base {
-class TimeTicks;
-}
-
-// A ResourceThrottle which defers request start, redirect, and response
-// completion on an IO to UI to IO round-trip. This throttle will be added on a
-// field trial to determine the cost of making some resource-related decisions
-// on the UI thread. See https://crbug.com/524228.
-class ThreadHopResourceThrottle : public content::ResourceThrottle {
- public:
-  ThreadHopResourceThrottle();
-  ~ThreadHopResourceThrottle() override;
-
-  static bool IsEnabled();
-
-  // content::ResourceThrottle:
-  void WillStartRequest(bool* defer) override;
-  void WillRedirectRequest(const net::RedirectInfo& redirect_info,
-                           bool* defer) override;
-  void WillProcessResponse(bool* defer) override;
-  const char* GetNameForLogging() const override;
-
- private:
-  void ResumeAfterThreadHop();
-  void Resume(const base::TimeTicks& time);
-
-  base::WeakPtrFactory<ThreadHopResourceThrottle> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(ThreadHopResourceThrottle);
-};
-
-#endif  // CHROME_BROWSER_RENDERER_HOST_THREAD_HOP_RESOURCE_THROTTLE_H_