Remove unused crw_web_controller.h include from preload_controller.mm

Bug: 620438
Change-Id: Iba4ec203858d779a2e91b45843b473349fd52e59
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2134567Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756298}

ios/chrome/browser/prerender/DEPS

-specific_include_rules = {
-  # TODO(crbug.com/620438): Remove this exception.
-  "^preload_controller\.mm$": [
-    "+ios/web/web_state/ui/crw_web_controller.h",
-  ],
-}

ios/chrome/browser/prerender/preload_controller.mm

@@ -32,7 +32,6 @@
 #include "ios/web/public/web_client.h"
 #import "ios/web/public/web_state.h"
 #import "ios/web/public/web_state_observer_bridge.h"
-#import "ios/web/web_state/ui/crw_web_controller.h"
 #import "net/base/mac/url_conversions.h"
 #include "ui/base/page_transition_types.h"