ios: Remove PreloadDelayWebStateReset test config.

Remove the variations config, but leaving the feature itself as a kill
switch.

Bug: 1032928
Change-Id: I83a98fa11df058cf23a9c75ca47c7d2ef03410e3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2610065
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Auto-Submit: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Ali Juma <ajuma@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841495}

ios/chrome/browser/prerender/preload_controller.mm

@@ -144,7 +144,7 @@ class PreloadJavaScriptDialogPresenter : public web::JavaScriptDialogPresenter {
 // Maximum time to let a cancelled webState attempt to finish restore.
 static const size_t kMaximumCancelledWebStateDelay = 2;
 
-// Used to enable the workaround for a WebKit crash, see crbug.com/1032928.
+// Kill switch guarding a workaround for a WebKit crash, see crbug.com/1032928.
 const base::Feature kPreloadDelayWebStateReset{
     "PreloadDelayWebStateReset", base::FEATURE_ENABLED_BY_DEFAULT};
 

testing/variations/fieldtrial_testing_config.json

@@ -3756,21 +3756,6 @@
             ]
         }
     ],
-    "IOSPreloadDelayWebStateReset": [
-        {
-            "platforms": [
-                "ios"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "PreloadDelayWebStateReset"
-                    ]
-                }
-            ]
-        }
-    ],
     "IOSRequestDesktopByDefault": [
         {
             "platforms": [