Temporarily dump without crashing when setting an empty PageState.

content/browser/web_contents/web_contents_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/browser/web_contents/web_contents_impl.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <utility>
 
 #include "base/command_line.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/feature_list.h"
 #include "base/lazy_instance.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram.h"
 #include "base/process/process.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 4497 matching lines @@
   // The SiteInstance might not match if we do a cross-process navigation with
   // replacement (e.g., auto-subframe), in which case the swap out of the old
   // RenderFrameHost runs in the background after the old FrameNavigationEntry
   // has already been replaced and destroyed.
   if (frame_entry->site_instance() != rfhi->GetSiteInstance())
     return;
 
   if (page_state == frame_entry->page_state())
     return;  // Nothing to update.
 
+  if (!page_state.IsValid()) {
+    // Temporarily generate a minidump to diagnose https://crbug.com/568703.
+    base::debug::DumpWithoutCrashing();
+    NOTREACHED() << "Shouldn't set an empty PageState.";
+  }
   frame_entry->set_page_state(page_state);
   controller_.NotifyEntryChanged(entry);
 }
 
 void WebContentsImpl::UpdateTitle(RenderFrameHost* render_frame_host,
                                   int32_t page_id,
                                   const base::string16& title,
                                   base::i18n::TextDirection title_direction) {
   // If we have a title, that's a pretty good indication that we've started
   // getting useful data.
@@ skipping 667 matching lines @@
   for (RenderViewHost* render_view_host : render_view_host_set)
     render_view_host->OnWebkitPreferencesChanged();
 }
 
 void WebContentsImpl::SetJavaScriptDialogManagerForTesting(
     JavaScriptDialogManager* dialog_manager) {
   dialog_manager_ = dialog_manager;
 }
 
 }  // namespace content