Add ref-count on RenderViewHost for each new RenderFrameProxyHost.

content/browser/frame_host/render_frame_host_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/containers/hash_tables.h"
 #include "base/lazy_instance.h"
@@ skipping 148 matching lines @@
       is_waiting_for_beforeunload_ack_(false),
       unload_ack_is_for_navigation_(false),
       is_loading_(false),
       pending_commit_(false),
       accessibility_reset_token_(0),
       accessibility_reset_count_(0),
       no_create_browser_accessibility_manager_for_testing_(false),
       weak_ptr_factory_(this) {
   bool is_swapped_out = !!(flags & CREATE_RF_SWAPPED_OUT);
   bool hidden = !!(flags & CREATE_RF_HIDDEN);
-  frame_tree_->RegisterRenderFrameHost(this);
+  frame_tree_->AddRenderViewHostRef(render_view_host_);
   GetProcess()->AddRoute(routing_id_, this);
   g_routing_id_frame_map.Get().insert(std::make_pair(
       RenderFrameHostID(GetProcess()->GetID(), routing_id_),
       this));
 
   if (is_swapped_out) {
     rfh_state_ = STATE_SWAPPED_OUT;
   } else {
     rfh_state_ = STATE_DEFAULT;
     GetSiteInstance()->increment_active_frame_count();
@@ skipping 20 matching lines @@
 
   FrameAccessibility::GetInstance()->OnRenderFrameHostDestroyed(this);
 
   // If this was swapped out, it already decremented the active frame count of
   // the SiteInstance it belongs to.
   if (IsRFHStateActive(rfh_state_))
     GetSiteInstance()->decrement_active_frame_count();
 
   // Notify the FrameTree that this RFH is going away, allowing it to shut down
   // the corresponding RenderViewHost if it is no longer needed.
-  frame_tree_->UnregisterRenderFrameHost(this);
+  frame_tree_->ReleaseRenderViewHostRef(render_view_host_);
 
   // NULL out the swapout timer; in crash dumps this member will be null only if
   // the dtor has run.
   swapout_event_monitor_timeout_.reset();
 
   for (const auto& iter: visual_state_callbacks_) {
     iter.second.Run(false);
   }
 
   if (render_widget_host_) {
@@ skipping 1847 matching lines @@
   // We may be returning to an existing NavigationEntry that had been granted
   // file access.  If this is a different process, we will need to grant the
   // access again.  The files listed in the page state are validated when they
   // are received from the renderer to prevent abuse.
   if (request_params.page_state.IsValid()) {
     render_view_host_->GrantFileAccessFromPageState(request_params.page_state);
   }
 }
 
 }  // namespace content