Implement PrerenderManager::AddPrerenderForOffline()

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 743d117f38ca0a3799144705869176d0a3602a41..765c95325d4ab914651347f13fe5ff55a3c84fcc 100644
--- a/chrome/browser/prerender/prerender_manager.cc
+++ b/chrome/browser/prerender/prerender_manager.cc
@@ -25,6 +25,7 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/net/prediction_options.h"
+#include "chrome/browser/prerender/prerender_constants.h"
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/prerender/prerender_field_trial.h"
 #include "chrome/browser/prerender/prerender_final_status.h"
@@ -325,6 +326,14 @@ PrerenderHandle* PrerenderManager::AddPrerenderForInstant(
                       session_storage_namespace);
 }
 
+PrerenderHandle* PrerenderManager::AddPrerenderForOffline(
+    const GURL& url,
+    content::SessionStorageNamespace* session_storage_namespace,
+    const gfx::Size& size) {
+  return AddPrerender(ORIGIN_OFFLINE, url, content::Referrer(), size,
+                      session_storage_namespace);
+}
+
 void PrerenderManager::CancelAllPrerenders() {
   DCHECK(CalledOnValidThread());
   while (!active_prerenders_.empty()) {
@@ -532,6 +541,9 @@ WebContents* PrerenderManager::SwapInternal(
     ScheduleDeleteOldWebContents(old_web_contents, NULL);
   }
 
+  // Offline originated prerenders should never ever be swapped-in.
+  DCHECK(prerender_contents->origin() != ORIGIN_OFFLINE);
+
   // TODO(cbentzel): Should prerender_contents move to the pending delete
   //                 list, instead of deleting directly here?
   AddToHistory(prerender_contents.get());
@@ -1104,6 +1116,9 @@ void PrerenderManager::PostCleanupTask() {
 
 base::TimeTicks PrerenderManager::GetExpiryTimeForNewPrerender(
     Origin origin) const {
+  if (origin == ORIGIN_OFFLINE)
+    return GetCurrentTimeTicks() + base::TimeDelta::FromMinutes(
+        kOfflinePrerenderLifeExpectancyMinutes);
   return GetCurrentTimeTicks() + config_.time_to_live;
 }
 
@@ -1174,6 +1189,8 @@ bool PrerenderManager::DoesRateLimitAllowPrerender(Origin origin) const {
   base::TimeDelta elapsed_time =
       GetCurrentTimeTicks() - last_prerender_start_time_;
   histograms_->RecordTimeBetweenPrerenderRequests(origin, elapsed_time);
+  if (origin == ORIGIN_OFFLINE)
+    return true;
   if (!config_.rate_limit_enabled)
     return true;
   return elapsed_time >=
@@ -1316,10 +1333,18 @@ NetworkPredictionStatus PrerenderManager::GetPredictionStatusForOrigin(
     Origin origin) const {
   DCHECK(CalledOnValidThread());
 
-  // LINK rel=prerender origins ignore the network state and the privacy
-  // settings.
+  // <link rel=prerender> origins ignore the network state and the privacy
+  // settings. Web developers should be able prefetch with all possible privacy
+  // settings and with all possible network types. This would avoid web devs
+  // coming up with creative ways to prefetch in cases they are not allowed to
+  // do so.
+  //
+  // Offline originated prerenders also ignore the network state and privacy
+  // settings because want to be able to snapshot webpages independently of

[pasko, 2016/04/05 11:49:56]

slight rephrasing: "because they are controlled by the offliner logic via
PrerenderHandle."

[gabadie, 2016/04/05 13:35:24]

Done.

+  // these former settings.
   if (origin == ORIGIN_LINK_REL_PRERENDER_SAMEDOMAIN ||
-      origin == ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN) {
+      origin == ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN ||
+      origin == ORIGIN_OFFLINE) {
     return NetworkPredictionStatus::ENABLED;
   }