Update prerender policy for custom tabs

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 e13ecf4849901aaa1ffa4f06581c1f7d96931cd4..898250319add08863d279ee7842a8faff170071c 100644
--- a/chrome/browser/prerender/prerender_origin.h
+++ b/chrome/browser/prerender/prerender_origin.h
@@ -23,6 +23,7 @@ enum Origin {
   ORIGIN_EXTERNAL_REQUEST = 10,
   ORIGIN_INSTANT = 11,
   ORIGIN_LINK_REL_NEXT = 12,
+  ORIGIN_EXTERNAL_REQUEST_MOBILE = 13,

[Benoit L, 2016/03/10 13:58:30]

I guess that you need to update places where this enum is used. At least for the
histograms:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/pre...

Fortunately, it doesn't seem to be used too widely, that is mainly for
histograms (we may want to conflate this with EXTERNAL_REQUEST) and throttling
(ditto?).


Also, should the name reflect that we force the prerender even though we're on a
mobile network?

Maybe ORIGIN_EXTERNAL_REQUEST_FORCED_ON_MOBILE?

[pasko, 2016/03/10 14:21:37]

+1, also would need a new suffix in histograms.xml

Maybe ORIGIN_EXTERNAL_REQUEST_FORCED, since the mechanics of PrerenderManager is
not mobile-specific. On the other hand, it is important to emphasize in the
origin what kind of hack it is. Maybe then
RIGIN_EXTERNAL_REQUEST_FORCED_CUSTOMTABS is even more descriptive. The offline
thing will probably use the same mechanics, but we would like the origin to be
different for UMA accounting reasons.

[Yusuf, 2016/03/10 18:55:53]

Done.

[Yusuf, 2016/03/10 18:55:53]

Done.

   ORIGIN_MAX,
 };