Add new prerender origin type for <link rel=next ...> launched prerenders.

Add new prerender origin type for <link rel=next ...> launched prerenders.

By adding rel=next as an origin, we get histogram reporting on many of
our existing histograms.

The one tricky decision is that a prerender can have multiple rel
types (both next and prerender), and that by origin we currently
distinguish samedomain vs crossdomain.

In this CL we treat a prerender with both next and prerender rel types
as rel=prerender, and we do not distinguish cross vs same domain on
rel=next prerenders.

R=tburkard,davidben,isherman@chromium.org
BUG=329963
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251139

[gavinp, 2013-12-26 19:47:17]

Timo, David, can you look this over before I invite in a histogram reviewer?

I'm a bit concerned about the explosion of histograms, and about dealing with
prerenders that are both "prerender" and "next". I think the logic of treating
both as "prerender" is solid, since we're trying to track new prerenders caused
by this API, which are all labeled "next."

Do you think we could contain histogram bloat by removing the same/cross site
distinction for rel=prerender? That'd make these more parallel, and we would
have zero bloat on this CL then.

[davidben, 2014-01-04 00:19:46]

LGTM. Treating prerender/next as just prerender seems reasonable. I imagine
"prerender next" will never actually occur anyway. :-)

Timo would have more of an opinion than me as to whether the same/cross site
distinction is worth keeping since I don't do much with the histograms.

https://codereview.chromium.org/121293002/diff/160001/chrome/browser/prerende...
File chrome/browser/prerender/prerender_manager.cc (right):

https://codereview.chromium.org/121293002/diff/160001/chrome/browser/prerende...
chrome/browser/prerender/prerender_manager.cc:329: ORIGIN_LINK_REL_NEXT;
Nit: I'm personally paranoid about C precedence and would probably put parens
around rel_types & PrerenderRelTypePrerender to be safe. (But if C does actually
interpret that the sensible way, I don't insist.)

[gavinp, 2014-02-07 20:58:32]

+isherman

isherman: PTAL.

Now rebased to trunk, and set downstream of
https://codereview.chromium.org/98603015/ .

[Ilya Sherman, 2014-02-07 21:37:38]

histograms lgtm

[gavinp, 2014-02-13 13:51:35]

The CQ bit was checked by gavinp@chromium.org

[commit-bot: I haz the power, 2014-02-13 13:52:00]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/121293002/430001

[commit-bot: I haz the power, 2014-02-13 13:52:04]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-02-13 13:52:05]

Failed to apply patch for chrome/browser/prerender/prerender_unittest.cc:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file chrome/browser/prerender/prerender_unittest.cc
  Hunk #1 FAILED at 859.
  1 out of 1 hunk FAILED -- saving rejects to file
chrome/browser/prerender/prerender_unittest.cc.rej

Patch:       chrome/browser/prerender/prerender_unittest.cc
Index: chrome/browser/prerender/prerender_unittest.cc
diff --git a/chrome/browser/prerender/prerender_unittest.cc
b/chrome/browser/prerender/prerender_unittest.cc
index
12cc4a8a1bfeb73bf15fcbba655bb431b1f6fda2..bf4d957b65f07fd1a20104309efcb0320df844a5
100644
--- a/chrome/browser/prerender/prerender_unittest.cc
+++ b/chrome/browser/prerender/prerender_unittest.cc
@@ -859,7 +859,7 @@ TEST_F(PrerenderTest, RelNextByFieldTrial) {
   GURL url("http://www.google.com/");
   DummyPrerenderContents* prerender_contents =
       prerender_manager()->CreateNextPrerenderContents(
-          url, FINAL_STATUS_MANAGER_SHUTDOWN);
+          url, ORIGIN_LINK_REL_NEXT, FINAL_STATUS_MANAGER_SHUTDOWN);
 
   prerender_link_manager()->OnAddPrerender(
       kDefaultChildId, GetNextPrerenderID(), url, PrerenderRelTypeNext,

[gavinp, 2014-02-13 17:07:35]

The CQ bit was checked by gavinp@chromium.org

[commit-bot: I haz the power, 2014-02-13 17:09:02]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/121293002/700001

[commit-bot: I haz the power, 2014-02-13 19:50:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/121293002/700001

[commit-bot: I haz the power, 2014-02-13 21:53:39]

Change committed as 251139