Introduce a field trial for Instant.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 1c99a681eea6126433660c3d1896459080fe54f5..f11e7d1d5421fdf135958526fd74af03136384ca 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -269,6 +269,10 @@ const char kInstantEnabledOnce[] = "instant.enabled_once";
 // Time when instant was last enabled.
 const char kInstantEnabledTime[] = "instant.enabled_time";
 
+// Random number drawn and used by the Instant field trial. Stored in prefs to
+// provide a consistent field trial experience across browser restarts.
+const char kInstantFieldTrialRandomDraw[] = "instant.field_trial_random_draw";

[jar (doing other things), 2011/07/22 01:42:17]

Although I understand why you're doing this... I think it is a bad idea, as it
unwittingly tags each user uniquely (I think), unless you make the resolution
rather low.  Perhaps an integer in the range of 1-100 would be sufficient for
your needs, and not provide such tagging.  WDYT?

[sreeram, 2011/07/22 14:31:16]

I think that's a fine idea! I'll change this to be a random integer in the range
[0, 10k). That will give us enough resolution to do groups of size 0.01%,
without uniquely marking the user.

+
 // Used to maintain instant promo keys. See PromoCounter for details of subkeys
 // that are used.
 const char kInstantPromo[] = "instant.promo";