Upstreaming prerendering changes for Android.

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 138785a7df0093d648f3140f3e8e18d95b94f2ff..88c698dd43e55ca010fa1d78ad938a7aace716d3 100644
--- a/chrome/browser/prerender/prerender_manager.cc
+++ b/chrome/browser/prerender/prerender_manager.cc
@@ -268,11 +268,17 @@ bool PrerenderManager::AddPrerenderFromLinkRelPrerender(
     int route_id,
     const GURL& url,
     const content::Referrer& referrer) {
+#if defined(OS_ANDROID)
+  // TODO(jcivelli): http://crbug.com/113322 We should have an option to disable
+  //                link-prerender and enable omnibox-prerender only.
+  return false;
+#else
   std::pair<int, int> child_route_id_pair = std::make_pair(process_id,
                                                            route_id);
 
   return AddPrerender(ORIGIN_LINK_REL_PRERENDER, child_route_id_pair,
                       url, referrer, NULL);
+#endif
 }
 
 bool PrerenderManager::AddPrerenderFromOmnibox(
@@ -634,6 +640,12 @@ bool PrerenderManager::IsWebContentsPrerendering(
   return false;
 }
 
+bool PrerenderManager::DidPrerenderFinishLoading(const GURL& url) {
+  DCHECK(CalledOnValidThread());
+  PrerenderContents* contents = FindEntry(url);
+  return contents ? contents->has_finished_loading() : false;
+}
+
 void PrerenderManager::MarkWebContentsAsPrerendered(WebContents* web_contents) {
   DCHECK(CalledOnValidThread());
   prerendered_tab_contents_set_.insert(web_contents);
@@ -828,11 +840,15 @@ bool PrerenderManager::AddPrerender(
   // true, so that case needs to be explicitly checked for.
   // TODO(tburkard): Figure out how to cancel prerendering in the opposite
   // case, when a new tab is added to a process used for prerendering.
+  // On Android we do reuse processes as we have a limited number of them and we
+  // still want the benefits or prerendering even when several tabs are open.

[dominich, 2012/02/14 01:11:20]

nit 'or prerendering' -> 'of prerendering'

[dominich, 2012/02/14 01:11:20]

This means that you can't lower the CPU process - have you measured the cost to
the user of mispredicting a prerender?

[Jay Civelli, 2012/02/14 03:13:51]

Done.

[Jay Civelli, 2012/02/14 03:13:51]

I thought there was only lower priority given to network requests from the
prerendered page and that we did not change the process priority? 
I compared the performances of the previous implementation (using the instant
code) and this one and saw no noticeable difference.

+#if !defined(OS_ANDROID)
   if (content::RenderProcessHost::ShouldTryToUseExistingProcessHost() &&
       !content::RenderProcessHost::run_renderer_in_process()) {
     RecordFinalStatus(origin, experiment, FINAL_STATUS_TOO_MANY_PROCESSES);
     return false;
   }
+#endif
 
   // Check if enough time has passed since the last prerender.
   if (!DoesRateLimitAllowPrerender()) {