Test theory about didCommitProvisionalLoad crash.

content/renderer/render_view_impl.cc

 // Copyright (c) 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.
 
 #include "content/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/auto_reset.h"
@@ skipping 673 matching lines @@
 
   if (params.main_frame_routing_id != MSG_ROUTING_NONE) {
     main_render_frame_ = RenderFrameImpl::CreateMainFrame(
         this, params.main_frame_routing_id, params.main_frame_widget_routing_id,
         params.hidden, screen_info(), compositor_deps_);
   }
 
   if (params.proxy_routing_id != MSG_ROUTING_NONE) {
     CHECK(params.swapped_out);
     if (main_render_frame_) {
-      DCHECK(!SiteIsolationPolicy::IsSwappedOutStateForbidden());
+      CHECK(!SiteIsolationPolicy::IsSwappedOutStateForbidden());

[Charlie Reis, 2016/01/22 18:00:51]

I suspect that we'll fail this check rather than crash in
didCommitProvisionalLoad, based on the params I saw in crash reports.  It looks
like the RenderView has *both* a main frame routing ID and a proxy ID, which (I
think) shouldn't be possible anymore.

       RenderFrameProxy* proxy = RenderFrameProxy::CreateProxyToReplaceFrame(
           main_render_frame_, params.proxy_routing_id,
           blink::WebTreeScopeType::Document);
       main_render_frame_->set_render_frame_proxy(proxy);
     } else {
-      DCHECK(SiteIsolationPolicy::IsSwappedOutStateForbidden());
+      CHECK(SiteIsolationPolicy::IsSwappedOutStateForbidden());
       // Pass MSG_ROUTING_NONE for opener, since actual opener (if any) will be
       // set separately below.
       RenderFrameProxy::CreateFrameProxy(params.proxy_routing_id, routing_id(),
                                          MSG_ROUTING_NONE, MSG_ROUTING_NONE,
                                          params.replicated_frame_state);
     }
   }
 
   if (main_render_frame_)
     main_render_frame_->Initialize();
@@ skipping 3016 matching lines @@
   if (IsUseZoomForDSFEnabled()) {
     webview()->setZoomFactorForDeviceScaleFactor(device_scale_factor_);
   } else {
     webview()->setDeviceScaleFactor(device_scale_factor_);
   }
   webview()->settings()->setPreferCompositingToLCDTextEnabled(
       PreferCompositingToLCDText(compositor_deps_, device_scale_factor_));
 }
 
 }  // namespace content