PlzNavigate: make content unit tests work with browser side navigation

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index f284e5765ae46ad8fe3d6ec78e6a8c38ec56c3af..edd4788a91f20d40b4396032a2dd9ae778b1068d 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -21,6 +21,7 @@
 #include "content/browser/frame_host/frame_tree.h"
 #include "content/browser/frame_host/frame_tree_node.h"
 #include "content/browser/frame_host/navigator.h"
+#include "content/browser/frame_host/navigator_impl.h"
 #include "content/browser/frame_host/render_frame_host_delegate.h"
 #include "content/browser/frame_host/render_frame_proxy_host.h"
 #include "content/browser/frame_host/render_widget_host_view_child_frame.h"
@@ -883,6 +884,15 @@ void RenderFrameHostImpl::OnBeforeUnloadACK(
     render_view_host_->GetDelegate()->DidCancelLoading();
 }
 
+bool RenderFrameHostImpl::IsWaitingForBeforeUnloadACK() const {
+  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableBrowserSideNavigation)) {
+    return is_waiting_for_beforeunload_ack_;
+  }
+  return frame_tree_node_->navigator()->IsWaitingForBeforeUnloadACK(
+      frame_tree_node_);
+}
+
 bool RenderFrameHostImpl::IsWaitingForUnloadACK() const {
   return render_view_host_->is_waiting_for_close_ack_ ||
       rfh_state_ == STATE_PENDING_SWAP_OUT;