[net] Re-enable async DNS field trial (on canary only)

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 b37028c905fe4c12ec5673cb8b6069f519d6c3c3..215ffdcf3a147b1c862b33aacffabe1b435c4876 100644
--- a/chrome/browser/net/async_dns_field_trial.cc
+++ b/chrome/browser/net/async_dns_field_trial.cc
@@ -18,9 +18,9 @@ bool ConfigureAsyncDnsFieldTrial() {
   const base::FieldTrial::Probability kAsyncDnsDivisor = 100;
   base::FieldTrial::Probability enabled_probability = 0;
 
-  // TODO(szym): bring the probability up after fixing http://crbug.com/121085
-  if (chrome::VersionInfo::GetChannel() <= chrome::VersionInfo::CHANNEL_DEV)
-    enabled_probability = 0;
+  // TODO(szym): expand to DEV channel after fixing http://crbug.com/121085
+  if (chrome::VersionInfo::GetChannel() <= chrome::VersionInfo::CHANNEL_CANARY)
+    enabled_probability = 50;
 
   scoped_refptr<base::FieldTrial> trial(
       base::FieldTrialList::FactoryGetFieldTrial(