Prerendered pages are swapped in at browser::Navigate time.

chrome/browser/prerender/prerender_contents.cc

 // Copyright (c) 2012 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 "chrome/browser/prerender/prerender_contents.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/process_util.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/history/history_tab_helper.h"
 #include "chrome/browser/history/history_types.h"
 #include "chrome/browser/prerender/prerender_final_status.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/prerender/prerender_render_view_host_observer.h"
 #include "chrome/browser/prerender/prerender_tracker.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/icon_messages.h"
-#include "chrome/common/render_messages.h"
+#include "chrome/common/prerender_messages.h"
 #include "chrome/common/url_constants.h"
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/renderer_host/resource_request_details.h"
 #include "content/public/browser/browser_child_process_host.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "content/public/browser/web_contents_view.h"
 #include "ui/gfx/rect.h"
@@ skipping 16 matching lines @@
   bool operator()(const GURL& url) const {
     return url.scheme() == url_.scheme() &&
            url.host() == url_.host() &&
            url.port() == url_.port() &&
            url.path() == url_.path() &&
            url.query() == url_.query();
   }
   GURL url_;
 };
 
+// Tells the render process at |child_id| whether |url| is a new prerendered
+// page, or whether |url| is being removed as a prerendered page. Currently
+// this will only inform the render process that created the prerendered page
+// with <link rel="prerender"> tags about it. This means that if the user
+// clicks on a link for a prerendered URL in a different page, the prerender
+// will not be swapped in.
+void InformRenderProcessAboutPrerender(const GURL& url,
+                                       bool is_add,
+                                       int child_id) {
+  if (child_id < 0)
+    return;
+  content::RenderProcessHost* render_process_host =
+      content::RenderProcessHost::FromID(child_id);
+  if (!render_process_host)
+    return;
+  IPC::Message* message = NULL;
+  if (is_add)
+    message = new PrerenderMsg_AddPrerenderURL(url);
+  else
+    message = new PrerenderMsg_RemovePrerenderURL(url);
+  render_process_host->Send(message);
+}
+
 }  // end namespace
 
 class PrerenderContentsFactoryImpl : public PrerenderContents::Factory {
  public:
   virtual PrerenderContents* CreatePrerenderContents(
       PrerenderManager* prerender_manager, PrerenderTracker* prerender_tracker,
       Profile* profile, const GURL& url, const content::Referrer& referrer,
       Origin origin, uint8 experiment_id) OVERRIDE {
     return new PrerenderContents(prerender_manager, prerender_tracker, profile,
                                  url, referrer, origin, experiment_id);
@@ skipping 146 matching lines @@
       page_id_(0),
       has_stopped_loading_(false),
       has_finished_loading_(false),
       final_status_(FINAL_STATUS_MAX),
       prerendering_has_started_(false),
       match_complete_status_(MATCH_COMPLETE_DEFAULT),
       prerendering_has_been_cancelled_(false),
       child_id_(-1),
       route_id_(-1),
       origin_(origin),
-      experiment_id_(experiment_id) {
+      experiment_id_(experiment_id),
+      creator_child_id_(-1) {
   DCHECK(prerender_manager != NULL);
 }
 
 bool PrerenderContents::Init() {
   return AddAliasURL(prerender_url_);
 }
 
 // static
 PrerenderContents::Factory* PrerenderContents::CreateFactory() {
   return new PrerenderContentsFactoryImpl();
 }
 
 void PrerenderContents::StartPrerendering(
     const RenderViewHost* source_render_view_host,
     content::SessionStorageNamespace* session_storage_namespace) {
   DCHECK(profile_ != NULL);
   DCHECK(!prerendering_has_started_);
   DCHECK(prerender_contents_.get() == NULL);
 
   prerendering_has_started_ = true;
+  DCHECK(creator_child_id_ == -1);
+  DCHECK(alias_urls_.size() == 1);
+  if (source_render_view_host)
+    creator_child_id_ = source_render_view_host->GetProcess()->GetID();
+  InformRenderProcessAboutPrerender(prerender_url_, true,
+                                    creator_child_id_);
+
   WebContents* new_contents = WebContents::Create(
       profile_, NULL, MSG_ROUTING_NONE, NULL, session_storage_namespace);
   prerender_contents_.reset(new TabContentsWrapper(new_contents));
   content::WebContentsObserver::Observe(new_contents);
 
   gfx::Rect tab_bounds = prerender_manager_->config().default_tab_bounds;
   if (source_render_view_host) {
     DCHECK(source_render_view_host->GetView() != NULL);
     WebContents* source_wc =
         source_render_view_host->GetDelegate()->GetAsWebContents();
@@ skipping 95 matching lines @@
   DCHECK(prerendering_has_been_cancelled_ ||
          final_status_ == FINAL_STATUS_USED);
   DCHECK(origin_ != ORIGIN_MAX);
 
   prerender_manager_->RecordFinalStatusWithMatchCompleteStatus(
       origin_,
       experiment_id_,
       match_complete_status_,
       final_status_);
 
-  if (child_id_ != -1 && route_id_ != -1)
+  if (child_id_ != -1 && route_id_ != -1) {
     prerender_tracker_->OnPrerenderingFinished(child_id_, route_id_);
+    for (std::vector<GURL>::const_iterator it = alias_urls_.begin();
+         it != alias_urls_.end();
+         ++it) {
+      InformRenderProcessAboutPrerender(*it, false, creator_child_id_);

[dominich, 2012/03/06 19:41:39]

Is there any way to pass a list in a message instead of sending a whole bunch of
messages? I imagine this will only be one or two in most cases, but it could be
more, right?

[cbentzel, 2012/03/06 19:45:27]

I'm not sure if the IPCs can handle a vector<GURL> style argument. I'll see.

You bring up a good point about "it could be more". We might want to add a cap
of max allowable number of alias URLs for a particular prerendered page, and
enforce that cap in AddAliasURL. 

+    }
+  }
 
   // If we still have a TabContents, clean up anything we need to and then
   // destroy it.
   if (prerender_contents_.get())
     delete ReleasePrerenderContents();
 
   // The following URLs are no longer rendering.
   prerender_tracker_->RemovePrerenderURLsOnUIThread(alias_urls_);
 }
 
@@ skipping 34 matching lines @@
 
         content::Details<RenderViewHost> new_render_view_host(details);
         OnRenderViewHostCreated(new_render_view_host.ptr());
 
         // When a new RenderView is created for a prerendering TabContents,
         // tell the new RenderView it's being used for prerendering before any
         // navigations occur.  Note that this is always triggered before the
         // first navigation, so there's no need to send the message just after
         // the TabContents is created.
         new_render_view_host->Send(
-            new ChromeViewMsg_SetIsPrerendering(
+            new PrerenderMsg_SetIsPrerendering(
                 new_render_view_host->GetRoutingID(),
                 true));
 
         // Make sure the size of the RenderViewHost has been passed to the new
         // RenderView.  Otherwise, the size may not be sent until the
         // RenderViewReady event makes it from the render process to the UI
         // thread of the browser process.  When the RenderView receives its
         // size, is also sets itself to be visible, which would then break the
         // visibility API.
         new_render_view_host->WasResized();
@@ skipping 36 matching lines @@
   if (https && !prerender_manager_->config().https_allowed) {
     Destroy(FINAL_STATUS_HTTPS);
     return false;
   }
   if (prerender_manager_->HasRecentlyBeenNavigatedTo(url)) {
     Destroy(FINAL_STATUS_RECENTLY_VISITED);
     return false;
   }
 
   alias_urls_.push_back(url);
+  InformRenderProcessAboutPrerender(url, true, creator_child_id_);
   prerender_tracker_->AddPrerenderURLOnUIThread(url);
   return true;
 }
 
 void PrerenderContents::AddAliasURLsFromOtherPrerenderContents(
     PrerenderContents* other_pc) {
   for (std::vector<GURL>::const_iterator it = other_pc->alias_urls_.begin();
        it != other_pc->alias_urls_.end();
        ++it) {
     alias_urls_.push_back(*it);
@@ skipping 170 matching lines @@
 bool PrerenderContents::IsCrossSiteNavigationPending() const {
   if (!prerender_contents_.get() || !prerender_contents_->web_contents())
     return false;
   const WebContents* web_contents = prerender_contents_->web_contents();
   return (web_contents->GetSiteInstance() !=
           web_contents->GetPendingSiteInstance());
 }
 
 
 }  // namespace prerender