Check BrowsingInstance before swapping prerenders.

content/browser/site_instance_impl.cc

Index: content/browser/site_instance_impl.cc
diff --git a/content/browser/site_instance_impl.cc b/content/browser/site_instance_impl.cc
index 9bb1e755d8f79cba7ed92396667d27d60b33f799..48b9580857250fb30fe468e1a251a60bba4c98b0 100644
--- a/content/browser/site_instance_impl.cc
+++ b/content/browser/site_instance_impl.cc
@@ -182,6 +182,10 @@ bool SiteInstanceImpl::IsRelatedSiteInstance(const SiteInstance* instance) {
                                          instance)->browsing_instance_.get();
 }
 
+size_t SiteInstanceImpl::GetRelatedActiveContentsCount() const {
+  return browsing_instance_->active_contents_count();
+}
+
 bool SiteInstanceImpl::HasWrongProcessForURL(const GURL& url) {
   // Having no process isn't a problem, since we'll assign it correctly.
   // Note that HasProcess() may return true if process_ is null, in
@@ -203,6 +207,14 @@ bool SiteInstanceImpl::HasWrongProcessForURL(const GURL& url) {
       GetProcess(), browsing_instance_->browser_context(), site_url);
 }
 
+void SiteInstanceImpl::IncrementRelatedActiveContentsCount() {
+  browsing_instance_->increment_active_contents_count();

[Charlie Reis, 2014/04/29 17:31:08]

These are one-liners that could be inlined, right?  Seems like we can define
them in the .h file and use unix_hacker_style names.

[davidben, 2014/04/29 21:31:40]

That would require BrowsingInstance to be included rather than just
forward-declared. *shrug* I can do that if it's still preferable.

...though it is odd that BrowsingInstance is currently forward-declared in
site_instance.h but not even exported from content/. Fixing that...

+}
+
+void SiteInstanceImpl::DecrementRelatedActiveContentsCount() {
+  browsing_instance_->decrement_active_contents_count();
+}
+
 void SiteInstanceImpl::set_render_process_host_factory(
     const RenderProcessHostFactory* rph_factory) {
   g_render_process_host_factory_ = rph_factory;