Implement PrerenderManager::AddPrerenderForOffline()

chrome/browser/prerender/prerender_origin.h

Index: chrome/browser/prerender/prerender_origin.h
diff --git a/chrome/browser/prerender/prerender_origin.h b/chrome/browser/prerender/prerender_origin.h
index 60e3e0b12f3aa0e23b7d8baed2a5499f99f4ada2..fbdaa68ef3a4e91143b975fb0380fde5451ef965 100644
--- a/chrome/browser/prerender/prerender_origin.h
+++ b/chrome/browser/prerender/prerender_origin.h
@@ -24,12 +24,16 @@ enum Origin {
   ORIGIN_INSTANT = 11,
   ORIGIN_LINK_REL_NEXT = 12,
   ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR = 13,
+  ORIGIN_OFFLINE = 14,

[pasko, 2016/04/04 12:55:56]

adding new origin requires changes in histograms.xml

There is a recent example of doing it here:
https://codereview.chromium.org/1767243002

[gabadie, 2016/04/04 14:05:07]

Done.

   ORIGIN_MAX,
 };
 
 // Return a human-readable name for |origin|.
 const char* NameFromOrigin(Origin origin);
 
+// Returns whether the origin should take care of the
+bool IsCellularForcedOrigin(Origin origin);
+
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_ORIGIN_H_