Disable support for swapped out RenderFrame(Host) on desktop.

content/browser/frame_host/frame_tree.cc

Index: content/browser/frame_host/frame_tree.cc
diff --git a/content/browser/frame_host/frame_tree.cc b/content/browser/frame_host/frame_tree.cc
index 680766435dbd5e742122d3188d7b2ea56a94e022..65d434fb08ea4ff0fe132316510450ffc415ae93 100644
--- a/content/browser/frame_host/frame_tree.cc
+++ b/content/browser/frame_host/frame_tree.cc
@@ -299,14 +299,20 @@ RenderViewHostImpl* FrameTree::CreateRenderViewHost(SiteInstance* site_instance,
                                     hidden));
 
   render_view_host_map_[site_instance->GetId()] = rvh;
+  LOG(ERROR) << "FT[" << this << "]::CreateRenderViewHost: "
+    << " created " << rvh << " with refcount:" << rvh->ref_count();
   return rvh;
 }
 
 RenderViewHostImpl* FrameTree::GetRenderViewHost(SiteInstance* site_instance) {
   RenderViewHostMap::iterator iter =
       render_view_host_map_.find(site_instance->GetId());
-  if (iter == render_view_host_map_.end())
+  if (iter == render_view_host_map_.end()) {
+    LOG(ERROR) << "FT[" << this << "]::GetRenderViewHost: "
+      << " could not find RVH for site:"
+      << site_instance->GetId() << "," << site_instance->GetSiteURL();
     return nullptr;
+  }
   return iter->second;
 }
 
@@ -318,6 +324,9 @@ void FrameTree::AddRenderViewHostRef(RenderViewHostImpl* render_view_host) {
   CHECK(iter->second == render_view_host);
 
   iter->second->increment_ref_count();
+  LOG(ERROR) << "FT[" << this << "]::AddRenderViewHostRef: "
+    << iter->second << "|" << iter->second->GetSiteInstance()->GetSiteURL()
+    << " up to " << iter->second->ref_count();
 }
 
 void FrameTree::ReleaseRenderViewHostRef(RenderViewHostImpl* render_view_host) {
@@ -330,11 +339,17 @@ void FrameTree::ReleaseRenderViewHostRef(RenderViewHostImpl* render_view_host) {
     // using it.
     CHECK_GT(iter->second->ref_count(), 0);
     iter->second->decrement_ref_count();
+    LOG(ERROR) << "FT[" << this << "]::ReleaseRenderViewHostRef: "
+      << iter->second << "|" << iter->second->GetSiteInstance()->GetSiteURL()
+      << " down to " << iter->second->ref_count();
     if (iter->second->ref_count() == 0) {
       iter->second->Shutdown();
       render_view_host_map_.erase(iter);
     }
   } else {
+    LOG(ERROR) << "FT[" << this << "]::ReleaseRenderViewHostRef: "
+      << site_instance_id << " not found in map:" << (iter != render_view_host_map_.end());
+
     // The RenderViewHost should be in the list of RenderViewHosts pending
     // shutdown.
     bool render_view_host_found = false;