Revert of Simplify RenderFrameImpl::decidePolicyForNavigation and avoid DCHECK

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index f4d007f7551cc14a10f555a42f6d7f81c24d0db8..0fe03c647e108e470c63b818949ba1f795a02eed 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -4979,10 +4979,13 @@
                         info.navigationType != blink::WebNavigationTypeReload);
 
     if (!should_fork && url.SchemeIs(url::kFileScheme)) {
-      // Fork non-file to file opens.  Note that this may fork unnecessarily if
-      // another tab (hosting a file or not) targeted this one before its
-      // initial navigation, but that shouldn't cause a problem.
-      should_fork = !old_url.SchemeIs(url::kFileScheme);
+      // Fork non-file to file opens.  Check the opener URL if this is the
+      // initial navigation in a newly opened window.
+      GURL source_url(old_url);
+      if (is_initial_navigation && source_url.is_empty() && frame_->opener())
+        source_url = frame_->opener()->top()->document().url();
+      DCHECK(!source_url.is_empty());
+      should_fork = !source_url.SchemeIs(url::kFileScheme);
     }
 
     if (!should_fork) {