Turn on AreCrossProcessFramesPossible by default.

content/common/site_isolation_policy.cc

 // 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.
 
 #include "content/common/site_isolation_policy.h"
 
 #include "base/command_line.h"
-#include "base/feature_list.h"
-#include "base/lazy_instance.h"
-#include "content/public/common/browser_side_navigation_policy.h"
-#include "content/public/common/content_client.h"
-#include "content/public/common/content_features.h"
 #include "content/public/common/content_switches.h"
 
 namespace content {
 
 // static
 bool SiteIsolationPolicy::AreCrossProcessFramesPossible() {
-  return UseDedicatedProcessesForAllSites() ||
-         IsTopDocumentIsolationEnabled() ||
-         GetContentClient()->IsSupplementarySiteIsolationModeEnabled() ||
-         base::FeatureList::IsEnabled(::features::kGuestViewCrossProcessFrames);
+  return true;
 }
 
 // static
 bool SiteIsolationPolicy::UseDedicatedProcessesForAllSites() {
   return base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kSitePerProcess);
 }
 
 // static
 bool SiteIsolationPolicy::IsTopDocumentIsolationEnabled() {
   // --site-per-process trumps --top-document-isolation.
   if (UseDedicatedProcessesForAllSites())
     return false;
 
   return base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kTopDocumentIsolation);
 }
 
 }  // namespace content