Move AsyncDns field trial to server-side control.

chrome/browser/net/async_dns_field_trial.cc

Index: chrome/browser/net/async_dns_field_trial.cc
diff --git a/chrome/browser/net/async_dns_field_trial.cc b/chrome/browser/net/async_dns_field_trial.cc
index 95ce472b48897f292f4db492b635c02d788dc9b0..5bb45cf1e217d550f30084cb19babe449a28f819 100644
--- a/chrome/browser/net/async_dns_field_trial.cc
+++ b/chrome/browser/net/async_dns_field_trial.cc
@@ -5,8 +5,8 @@
 #include "chrome/browser/net/async_dns_field_trial.h"
 
 #include "base/metrics/field_trial.h"
+#include "base/memory/ref_counted.h"

[SteveT, 2012/10/25 03:00:27]

nit: Header out of order?

[szym, 2012/10/25 17:17:45]

Done.

 #include "build/build_config.h"
-#include "chrome/common/chrome_version_info.h"
 
 namespace chrome_browser_net {
 

[SteveT, 2012/10/25 03:00:27]

check: BTW the header comment is still applies in the exact same way, yeah?

[szym, 2012/10/25 03:03:13]

Thanks for catching that. The header comment is 2 CLs out of date.

[szym, 2012/10/25 17:17:45]

Done.

@@ -15,18 +15,14 @@ bool ConfigureAsyncDnsFieldTrial() {
   // There is no DnsConfigService on those platforms so disable the field trial.
   return false;
 #endif
-  const base::FieldTrial::Probability kAsyncDnsDivisor = 100;
-  base::FieldTrial::Probability enabled_probability = 0;
+  scoped_refptr<base::FieldTrial> trial(base::FieldTrialList::Find("AsyncDns"));

[Alexei Svitkine (slow), 2012/10/25 14:37:46]

You could simplify all of this by just getting the group name via:

base::FieldTrialList::FindFullName("AsyncDns")

If the trial doesn't exist, it will return an empty string.

[szym, 2012/10/25 17:17:45]

Done.

 
-  if (chrome::VersionInfo::GetChannel() <= chrome::VersionInfo::CHANNEL_DEV)
-    enabled_probability = 50;
+  if (!trial.get())
+    return false;
 

[SteveT, 2012/10/25 03:00:27]

nit: Maybe have a comment here on how the two choices are AsyncDnsA and
AsyncDnsB so this is a little less voodoo-looking.

[szym, 2012/10/25 17:17:45]

Done.

-  scoped_refptr<base::FieldTrial> trial(
-      base::FieldTrialList::FactoryGetFieldTrial(
-          "AsyncDns", kAsyncDnsDivisor, "disabled", 2012, 10, 30, NULL));
-
-  int enabled_group = trial->AppendGroup("enabled", enabled_probability);
-  return trial->group() == enabled_group;
+  const std::string kAsyncDnsPrefix("AsyncDns");
+  return trial->group_name().compare(0, kAsyncDnsPrefix.length(),
+                                     kAsyncDnsPrefix) == 0;
 }
 
 }  // namespace chrome_browser_net