Additional fixes for prerender/instant + browsing history.

content/browser/tab_contents/tab_contents.cc

Index: content/browser/tab_contents/tab_contents.cc
diff --git a/content/browser/tab_contents/tab_contents.cc b/content/browser/tab_contents/tab_contents.cc
index 0b06b975200dce0dce4aec261d136bed54ff41aa..c57c590f993fdcfc32ad3ea8edeaa42a87619648 100644
--- a/content/browser/tab_contents/tab_contents.cc
+++ b/content/browser/tab_contents/tab_contents.cc
@@ -596,12 +596,16 @@ bool TabContents::NavigateToEntry(
   return true;
 }
 
-void TabContents::SetHistoryLengthAndClear(int history_length) {
+void TabContents::SetHistoryLengthAndPrune(const SiteInstance* site_instance,
+                                           int history_length,
+                                           int32 minimum_page_id) {
   RenderViewHost* rvh = render_view_host();
   if (!rvh)
     return;
-  rvh->Send(new ViewMsg_SetHistoryLengthAndClear(rvh->routing_id(),
-                                                 history_length));
+  DCHECK(!site_instance || rvh->site_instance() == site_instance);

[Charlie Reis, 2011/08/13 06:26:27]

As discussed, please either make this return early, or DCHECK that there is no
pending RVH (and ensure that's true by canceling prerendering if a cross-site
navigation is attempted).

[cbentzel, 2011/08/13 14:31:14]

Fixed. I early return in a number of unexpected cases and added NOTREACHED
clauses. This patch also adds logic for prerender where a page will be cancelled
if cross-site navigation is pending. If it had committed earlier during a
prerender, we still proceed. I have tested that case by doing a prerender of a
URL I have installed as an app. 

+  rvh->Send(new ViewMsg_SetHistoryLengthAndPrune(rvh->routing_id(),
+                                                 history_length,
+                                                 minimum_page_id));
 }
 
 void TabContents::Stop() {