Prerendered tabs use the same SessionStorage namespace as the tab that triggered the prerender.

chrome/browser/prerender/prerender_manager.cc

Index: chrome/browser/prerender/prerender_manager.cc
diff --git a/chrome/browser/prerender/prerender_manager.cc b/chrome/browser/prerender/prerender_manager.cc
index f7264ce95a23aa439a2cc25792e3329bc679cdf8..89fca760caba145383339a6f7b0d3d945cc7b479 100644
--- a/chrome/browser/prerender/prerender_manager.cc
+++ b/chrome/browser/prerender/prerender_manager.cc
@@ -35,6 +35,7 @@
 #include "content/browser/browser_thread.h"
 #include "content/browser/cancelable_request.h"
 #include "content/browser/debugger/render_view_devtools_agent_host.h"
+#include "content/browser/in_process_webkit/session_storage_namespace.h"
 #include "content/browser/renderer_host/render_process_host.h"
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/renderer_host/resource_dispatcher_host.h"
@@ -272,10 +273,13 @@ bool PrerenderManager::AddPrerenderFromLinkRelPrerender(int process_id,
                                                            route_id);
 
   return AddPrerender(ORIGIN_LINK_REL_PRERENDER, child_route_id_pair,
-                      url, referrer);
+                      url, referrer, NULL);
 }
 
-bool PrerenderManager::AddPrerenderFromOmnibox(const GURL& url) {
+bool PrerenderManager::AddPrerenderFromOmnibox(
+    const GURL& url,
+    SessionStorageNamespace* session_storage_namespace) {

[dominich, 2011/10/26 21:57:56]

A SessionStorageNamespace really doesn't make sense here. We might have one, but
it won't have anything in it, so passing one in and storing it is redundant.

Could we instead store NULL (or a null id) and check for that when checking
equivalence?

[cbentzel, 2011/10/26 22:03:48]

Actually, a namespace makes sense here. In this case, it is simply for the tab
rather than the tab+origin of the domain.

We also need to establish the namespace at the time that the RenderView for the
prerendered page is created. If it's not done, it will use a different one than
the tab that could be swapped in.

+  DCHECK(session_storage_namespace);
   if (!IsOmniboxEnabled(profile_))
     return false;
 
@@ -294,14 +298,16 @@ bool PrerenderManager::AddPrerenderFromOmnibox(const GURL& url) {
       break;
   };
 
-  return AddPrerender(origin, std::make_pair(-1, -1), url, GURL());
+  return AddPrerender(origin, std::make_pair(-1, -1), url, GURL(),
+                      session_storage_namespace);
 }
 
 bool PrerenderManager::AddPrerender(
     Origin origin,
     const std::pair<int, int>& child_route_id_pair,
     const GURL& url_arg,
-    const GURL& referrer) {
+    const GURL& referrer,
+    SessionStorageNamespace* session_storage_namespace) {
   DCHECK(CalledOnValidThread());
 
   if (origin == ORIGIN_LINK_REL_PRERENDER && IsGoogleSearchResultURL(referrer))
@@ -356,7 +362,6 @@ bool PrerenderManager::AddPrerender(
   }
 
   RenderViewHost* source_render_view_host = NULL;
-  // This test should fail only during unit tests.
   if (child_route_id_pair.first != -1) {
     source_render_view_host =
         RenderViewHost::FromID(child_route_id_pair.first,
@@ -370,8 +375,14 @@ bool PrerenderManager::AddPrerender(
     }
   }
 
-  PrerenderContents* prerender_contents =
-      CreatePrerenderContents(url, referrer, origin, experiment);
+  if (!session_storage_namespace) {
+    DCHECK(source_render_view_host);
+    session_storage_namespace =
+        source_render_view_host->session_storage_namespace();
+  }
+
+  PrerenderContents* prerender_contents = CreatePrerenderContents(
+      session_storage_namespace, url, referrer, origin, experiment);
   if (!prerender_contents || !prerender_contents->Init())
     return false;
 
@@ -535,6 +546,20 @@ bool PrerenderManager::MaybeUsePrerenderedPage(TabContents* tab_contents,
     return false;
   }
 
+  // If the sessionStorage namespaces don't match, don't swap the site in.
+  // Note that we don't actually need to destroy here.
+  RenderViewHost* old_render_view_host = tab_contents->render_view_host();
+  RenderViewHost* new_render_view_host =
+      prerender_contents->prerender_contents()->render_view_host();
+  DCHECK(old_render_view_host);
+  DCHECK(new_render_view_host);
+  if (old_render_view_host->session_storage_namespace()->id() !=

[dominich, 2011/10/26 21:57:56]

As you're checking ids here, why not just store the id instead of a pointer to
the namespace?

[cbentzel, 2011/10/26 22:03:48]

I mentioned that earlier in the CL as a possibility. It will require changes to
SessionStorageNamespace. 

Basically, there are two things we are using the SessionStorageNamespace for:

  - Comparing id's at the time that the prerendered view is swapped in.
  - Sending down a namespace to the prerendered RenderView at the time of it's
creation, which needs to match.

We could probably just hold onto an id if we changed the SessionStorageNamespace
to have a public constructor which takes an id at the time we create the
prerendered TabContents.

+      new_render_view_host->session_storage_namespace()->id()) {
+    prerender_contents.release()->Destroy(
+        FINAL_STATUS_SESSION_STORAGE_NAMESPACE_MISMATCH);
+    return false;
+  }
+
   int child_id, route_id;
   CHECK(prerender_contents->GetChildId(&child_id));
   CHECK(prerender_contents->GetRouteId(&route_id));
@@ -554,11 +579,8 @@ bool PrerenderManager::MaybeUsePrerenderedPage(TabContents* tab_contents,
   histograms_->RecordPerSessionCount(++prerenders_per_session_count_);
   prerender_contents->set_final_status(FINAL_STATUS_USED);
 
-  RenderViewHost* render_view_host =
-      prerender_contents->prerender_contents()->render_view_host();
-  DCHECK(render_view_host);
-  render_view_host->Send(
-      new ChromeViewMsg_SetIsPrerendering(render_view_host->routing_id(),
+  new_render_view_host->Send(
+      new ChromeViewMsg_SetIsPrerendering(new_render_view_host->routing_id(),
                                           false));
 
   TabContentsWrapper* new_tab_contents =
@@ -648,13 +670,15 @@ bool PrerenderManager::IsPrerenderElementFresh(const base::Time start) const {
 }
 
 PrerenderContents* PrerenderManager::CreatePrerenderContents(
+    SessionStorageNamespace* session_storage_namespace,
     const GURL& url,
     const GURL& referrer,
     Origin origin,
     uint8 experiment_id) {
   DCHECK(CalledOnValidThread());
   return prerender_contents_factory_->CreatePrerenderContents(
-      this, prerender_tracker_, profile_, url, referrer, origin, experiment_id);
+      this, prerender_tracker_, session_storage_namespace, profile_, url,
+      referrer, origin, experiment_id);
 }
 
 bool PrerenderManager::IsPendingDelete(PrerenderContents* entry) const {