Don't crash for subframes after in-page navigations in --site-per-process.

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 934885c95a21dfcda409671264ce68d02bce7aaa..1adb2be5d700a2f168971c42864488bf3594f81b 100644
--- a/content/browser/frame_host/navigation_entry_impl.cc
+++ b/content/browser/frame_host/navigation_entry_impl.cc
@@ -547,10 +547,8 @@ void NavigationEntryImpl::AddOrUpdateFrameEntry(FrameTreeNode* frame_tree_node,
       FindFrameEntry(frame_tree_node->parent());
   if (!parent_node) {
     // The renderer should not send a commit for a subframe before its parent.
-    // TODO(creis): Kill the renderer if we get here.  For now, crash to
-    // diagnose https://crbug.com/522193, since we most likely fail here when
-    // creating the first subframe entry before the CloneAndReplace call fails.
-    CHECK(false) << "Shouldn't see a commit for a subframe before parent.";
+    // TODO(creis): Kill the renderer if we get here.
+    return;
   }
 
   // Now check whether we have a TreeNode for the node itself.