Remove unused protocol PrerenderDelegate.

Bug: 754050
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I455f44efdbc02214a51d182460baeb1ab224383d
Reviewed-on: https://chromium-review.googlesource.com/728334Reviewed-by: Rohit Rao (ping after 24h) <rohitrao@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510192}

ios/chrome/browser/tabs/tab.mm

@@ -89,7 +89,6 @@
 #import "ios/chrome/browser/ui/fullscreen_controller.h"
 #import "ios/chrome/browser/ui/open_in_controller.h"
 #import "ios/chrome/browser/ui/overscroll_actions/overscroll_actions_controller.h"
-#import "ios/chrome/browser/ui/prerender_delegate.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #import "ios/chrome/browser/web/external_app_launcher.h"
 #import "ios/chrome/browser/web/navigation_manager_util.h"
@@ -1328,8 +1327,6 @@ void TabInfoBarObserver::OnInfoBarReplaced(infobars::InfoBar* old_infobar,
   [self.passKitDialogProvider presentPassKitDialog:data];
 }
 
-#pragma mark - PrerenderDelegate
-
 - (void)discardPrerender {
   DCHECK(_isPrerenderTab);
   [delegate_ discardPrerender];

ios/chrome/browser/ui/BUILD.gn

@@ -240,7 +240,6 @@ source_set("ui_internal") {
     "open_in_toolbar.mm",
     "page_not_available_controller.h",
     "page_not_available_controller.mm",
-    "prerender_delegate.h",
   ]
   deps = [
     ":resources",

ios/chrome/browser/ui/prerender_delegate.h

-// Copyright 2012 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_CHROME_BROWSER_UI_PRERENDER_DELEGATE_H_
-#define IOS_CHROME_BROWSER_UI_PRERENDER_DELEGATE_H_
-
-// A protocol for accessing and commanding prerenderer.
-@protocol PrerenderDelegate
-@optional
-// Discard prerenderer (e.g. when a dialog was suppressed).
-- (void)discardPrerender;
-// Is pre-render tab.
-- (BOOL)isPrerenderTab;
-@end
-
-#endif  // IOS_CHROME_BROWSER_UI_PRERENDER_DELEGATE_H_