Always swap with a replacement proxy in OnSwapOut.

content/browser/frame_host/frame_tree.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/frame_tree.h"
 
 #include <stddef.h>
 
 #include <queue>
 #include <utility>
@@ skipping 285 matching lines @@
 }
 
 RenderViewHostImpl* FrameTree::CreateRenderViewHost(
     SiteInstance* site_instance,
     int32_t routing_id,
     int32_t main_frame_routing_id,
     bool swapped_out,
     bool hidden) {
   RenderViewHostMap::iterator iter =
       render_view_host_map_.find(site_instance->GetId());
-  if (iter != render_view_host_map_.end()) {
-    // If a RenderViewHost is pending deletion for this |site_instance|, it
-    // shouldn't be reused, so put it in the map of RenderViewHosts pending
-    // shutdown.  Otherwise, return the existing RenderViewHost for the
-    // SiteInstance.  Note that if swapped-out is forbidden, the
-    // RenderViewHost's main frame has already been cleared, so we cannot rely
-    // on checking whether the main frame is pending deletion.
-    if (root_->render_manager()->IsViewPendingDeletion(iter->second)) {
-      render_view_host_pending_shutdown_map_.insert(
-          std::make_pair(site_instance->GetId(), iter->second));
-      render_view_host_map_.erase(iter);
-    } else {
-      return iter->second;
-    }
-  }
+  if (iter != render_view_host_map_.end())
+    return iter->second;
+
   RenderViewHostImpl* rvh =
       static_cast<RenderViewHostImpl*>(RenderViewHostFactory::Create(
           site_instance, render_view_delegate_, render_widget_delegate_,
           routing_id, main_frame_routing_id, swapped_out, hidden));
 
   render_view_host_map_[site_instance->GetId()] = rvh;
   return rvh;
 }
 
 RenderViewHostImpl* FrameTree::GetRenderViewHost(SiteInstance* site_instance) {
   RenderViewHostMap::iterator iter =
       render_view_host_map_.find(site_instance->GetId());
-  // Don't return the RVH if it is pending deletion.
-  if (iter != render_view_host_map_.end() &&
-      !root_->render_manager()->IsViewPendingDeletion(iter->second)) {
+  if (iter != render_view_host_map_.end())
     return iter->second;
-  }
+
   return nullptr;
 }
 
 void FrameTree::AddRenderViewHostRef(RenderViewHostImpl* render_view_host) {
   SiteInstance* site_instance = render_view_host->GetSiteInstance();
   RenderViewHostMap::iterator iter =
       render_view_host_map_.find(site_instance->GetId());
   CHECK(iter != render_view_host_map_.end());
   CHECK(iter->second == render_view_host);
 
   iter->second->increment_ref_count();
 }
 
 void FrameTree::ReleaseRenderViewHostRef(RenderViewHostImpl* render_view_host) {
   SiteInstance* site_instance = render_view_host->GetSiteInstance();
   int32_t site_instance_id = site_instance->GetId();
   RenderViewHostMap::iterator iter =
       render_view_host_map_.find(site_instance_id);
-  if (iter != render_view_host_map_.end() && iter->second == render_view_host) {
-    // Decrement the refcount and shutdown the RenderViewHost if no one else is
-    // using it.
-    CHECK_GT(iter->second->ref_count(), 0);
-    iter->second->decrement_ref_count();
-    if (iter->second->ref_count() == 0) {
-      iter->second->ShutdownAndDestroy();
-      render_view_host_map_.erase(iter);
-    }
-  } else {
-    // The RenderViewHost should be in the list of RenderViewHosts pending
-    // shutdown.
-    bool render_view_host_found = false;
-    std::pair<RenderViewHostMultiMap::iterator,
-              RenderViewHostMultiMap::iterator> result =
-        render_view_host_pending_shutdown_map_.equal_range(site_instance_id);
-    for (RenderViewHostMultiMap::iterator multi_iter = result.first;
-         multi_iter != result.second;
-         ++multi_iter) {
-      if (multi_iter->second != render_view_host)
-        continue;
-      render_view_host_found = true;
-      // Decrement the refcount and shutdown the RenderViewHost if no one else
-      // is using it.
-      CHECK_GT(render_view_host->ref_count(), 0);
-      render_view_host->decrement_ref_count();
-      if (render_view_host->ref_count() == 0) {
-        render_view_host->ShutdownAndDestroy();
-        render_view_host_pending_shutdown_map_.erase(multi_iter);
-      }
-      break;
-    }
-    CHECK(render_view_host_found);
+
+  CHECK(iter != render_view_host_map_.end());

[Charlie Reis, 2016/04/22 19:11:33]

Would CHECK_NE work?

[alexmos, 2016/04/25 18:17:07]

I had that originally, but that failed to compile in PS9.

[Charlie Reis, 2016/04/26 05:06:36]

Acknowledged.

+  CHECK_EQ(iter->second, render_view_host);
+
+  // Decrement the refcount and shutdown the RenderViewHost if no one else is
+  // using it.
+  CHECK_GT(iter->second->ref_count(), 0);
+  iter->second->decrement_ref_count();
+  if (iter->second->ref_count() == 0) {
+    iter->second->ShutdownAndDestroy();
+    render_view_host_map_.erase(iter);
   }
 }
 
 void FrameTree::FrameRemoved(FrameTreeNode* frame) {
   if (frame->frame_tree_node_id() == focused_frame_tree_node_id_)
     focused_frame_tree_node_id_ = -1;
 
   // No notification for the root frame.
   if (!frame->parent()) {
     CHECK_EQ(frame, root_);
@@ skipping 63 matching lines @@
   // This is only used to set page-level focus in cross-process subframes, and
   // requests to set focus in main frame's SiteInstance are ignored.
   if (instance != root_manager->current_frame_host()->GetSiteInstance()) {
     RenderFrameProxyHost* proxy =
         root_manager->GetRenderFrameProxyHost(instance);
     proxy->Send(new InputMsg_SetFocus(proxy->GetRoutingID(), is_focused));
   }
 }
 
 }  // namespace content