Temporarily dump without crashing when setting an empty PageState.

content/browser/frame_host/navigation_entry_impl.cc

Index: content/browser/frame_host/navigation_entry_impl.cc
diff --git a/content/browser/frame_host/navigation_entry_impl.cc b/content/browser/frame_host/navigation_entry_impl.cc
index 9250e6811a31745d126c71bf78b67cae448382cd..97413c7b639baf003f4afc20a781f3c034f989d5 100644
--- a/content/browser/frame_host/navigation_entry_impl.cc
+++ b/content/browser/frame_host/navigation_entry_impl.cc
@@ -9,6 +9,7 @@
 #include <queue>
 #include <utility>
 
+#include "base/debug/dump_without_crashing.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
@@ -52,6 +53,11 @@ void RecursivelyGenerateFrameEntries(const ExplodedFrameState& state,
   page_state.top = state;
   std::string data;
   EncodePageState(page_state, &data);
+  if (data.empty()) {
+    // Temporarily generate a minidump to diagnose https://crbug.com/568703.
+    base::debug::DumpWithoutCrashing();
+    NOTREACHED() << "Shouldn't generate an empty PageState.";
+  }
   node->frame_entry->set_page_state(PageState::CreateFromEncodedData(data));
 
   for (const ExplodedFrameState& child_state : state.children) {
@@ -745,6 +751,14 @@ void NavigationEntryImpl::AddOrUpdateFrameEntry(
     return;
   }
 
+  // We should only have an empty PageState if the navigation is new, and thus
+  // page ID is -1.
+  if (!page_state.IsValid() && GetPageID() != -1) {
+    // Temporarily generate a minidump to diagnose https://crbug.com/568703.
+    base::debug::DumpWithoutCrashing();
+    NOTREACHED() << "Shouldn't set an empty PageState.";
+  }
+
   // Now check whether we have a TreeNode for the node itself.
   const std::string& unique_name = frame_tree_node->unique_name();
   for (TreeNode* child : parent_node->children) {