Enable spare RenderProcessHost to be preinitialized.

content/browser/frame_host/render_frame_host_manager.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_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <string>
@@ skipping 1182 matching lines @@
 
   scoped_refptr<SiteInstance> new_instance =
       ConvertToSiteInstance(new_instance_descriptor, candidate_instance);
   // If |force_swap| is true, we must use a different SiteInstance than the
   // current one. If we didn't, we would have two RenderFrameHosts in the same
   // SiteInstance and the same frame, breaking lookup of RenderFrameHosts by
   // SiteInstance.
   if (force_swap)
     CHECK_NE(new_instance, current_instance);
 
+  if (new_instance == current_instance) {
+    // If we're navigating to the same site instance, we won't need to use any
+    // spare RenderProcessHost.
+    RenderProcessHostImpl::CleanupSpareRenderProcessHost();
+  }
+
   // Double-check that the new SiteInstance is associated with the right
   // BrowserContext.
   DCHECK_EQ(new_instance->GetBrowserContext(), browser_context);
 
   // If |new_instance| is a new SiteInstance for a subframe with an isolated
   // origin, set its process reuse policy so that such subframes are
   // consolidated into existing processes for that isolated origin.
   SiteInstanceImpl* new_instance_impl =
       static_cast<SiteInstanceImpl*>(new_instance.get());
   auto* policy = ChildProcessSecurityPolicyImpl::GetInstance();
@@ skipping 1615 matching lines @@
                       ->is_hidden() != delegate_->IsHidden()) {
     if (delegate_->IsHidden()) {
       view->Hide();
     } else {
       view->Show();
     }
   }
 }
 
 }  // namespace content