Enforce all subframes to be in the same BrowsingInstance as the parent.

content/test/web_contents_observer_sanity_checker.cc

 // Copyright 2014 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/test/web_contents_observer_sanity_checker.h"
 
 #include "base/strings/stringprintf.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "content/common/frame_messages.h"
 #include "content/public/browser/navigation_handle.h"
@@ skipping 36 matching lines @@
   }
 
   CHECK(render_frame_host->GetProcess()->HasConnection())
       << "RenderFrameCreated was called for a RenderFrameHost whose render "
          "process is not currently live, so there's no way for the RenderFrame "
          "to have been created.";
   CHECK(
       static_cast<RenderFrameHostImpl*>(render_frame_host)->IsRenderFrameLive())
       << "RenderFrameCreated called on for a RenderFrameHost that thinks it is "
          "not alive.";
+
+  // Any child frame must be in the same BrowsingInstance as its parent.
+  if (render_frame_host->GetParent()) {
+    CHECK(render_frame_host->GetSiteInstance()->IsRelatedSiteInstance(
+        render_frame_host->GetParent()->GetSiteInstance()));
+  }
 }
 
 void WebContentsObserverSanityChecker::RenderFrameDeleted(
     RenderFrameHost* render_frame_host) {
   CHECK(!web_contents_destroyed_);
   std::pair<int, int> routing_pair =
       std::make_pair(render_frame_host->GetProcess()->GetID(),
                      render_frame_host->GetRoutingID());
   bool was_live = !!live_routes_.erase(routing_pair);
   bool was_dead_already = !deleted_routes_.insert(routing_pair).second;
@@ skipping 249 matching lines @@
       render_frame_host->GetSiteInstance()->GetSiteURL().spec().c_str());
 }
 
 bool WebContentsObserverSanityChecker::NavigationIsOngoing(
     NavigationHandle* navigation_handle) {
   auto it = ongoing_navigations_.find(navigation_handle);
   return it != ongoing_navigations_.end();
 }
 
 }  // namespace content