Temporarily dump without crashing when setting an empty PageState.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 7e7b524ff1027ff1fc97585cffa148168d0b4291..8b03636cca36a6fd552c446e29280d98d62bc2b1 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -10,6 +10,7 @@
 #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"
@@ -4527,6 +4528,11 @@ void WebContentsImpl::UpdateStateForFrame(RenderFrameHost* render_frame_host,
   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);
 }