Implement PrerenderManager::AddPrerenderForOffline()

chrome/browser/prerender/prerender_origin.cc

Index: chrome/browser/prerender/prerender_origin.cc
diff --git a/chrome/browser/prerender/prerender_origin.cc b/chrome/browser/prerender/prerender_origin.cc
index 3c9b7b692492c76636cefcc609a118eac0914329..d222dea5c41f5455b7ae93011f87583e9f628a1c 100644
--- a/chrome/browser/prerender/prerender_origin.cc
+++ b/chrome/browser/prerender/prerender_origin.cc
@@ -27,6 +27,7 @@ const char* kOriginNames[] = {
   "Instant",
   "Link Rel Next",
   "External Request Forced Cellular",
+  "Offline",
   "Max",
 };
 static_assert(arraysize(kOriginNames) == ORIGIN_MAX + 1,
@@ -40,4 +41,28 @@ const char* NameFromOrigin(Origin origin) {
   return kOriginNames[origin];
 }
 
+bool IsAlwaysPrerenderedOrigin(Origin origin) {
+  DCHECK(static_cast<int>(origin) >= 0 &&
+         origin < ORIGIN_MAX);
+  // <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
+  // these former settings.
+  return origin == ORIGIN_LINK_REL_PRERENDER_SAMEDOMAIN ||
+         origin == ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN ||
+         origin == ORIGIN_OFFLINE;
+}
+
+bool IsCellularForcedOrigin(Origin origin) {
+  DCHECK(static_cast<int>(origin) >= 0 &&
+         origin < ORIGIN_MAX);
+  return origin == ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR ||
+         IsAlwaysPrerenderedOrigin(origin);
+}
+
 }  // namespace prerender