DNS: Per-network-type and Finch-variable timeouts

net/dns/dns_util.cc

Index: net/dns/dns_util.cc
diff --git a/net/dns/dns_util.cc b/net/dns/dns_util.cc
index d2897ff2ae0438dac06ec2e7b810ab1266c4cc83..c6b188d29305574b11b859406a7ef138885c2e86 100644
--- a/net/dns/dns_util.cc
+++ b/net/dns/dns_util.cc
@@ -9,6 +9,9 @@
 
 #include <cstring>
 
+#include "base/metrics/field_trial.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
 #include "build/build_config.h"
 
 #if defined(OS_POSIX)
@@ -152,4 +155,39 @@ bool HaveOnlyLoopbackAddresses() {
 #endif  // defined(various platforms)
 }
 
+#if !defined(OS_NACL)
+namespace {
+
+bool GetTimeDeltaForConnectionTypeFromFieldTrial(
+    const char* field_trial,
+    NetworkChangeNotifier::ConnectionType type_int,

[Randy Smith (Not in Mondays), 2016/03/15 20:12:30]

I mildly object to the naming; other variables of this type are just named
"type", and type"int is in relation to the unusual thing done below (the size_t
version), so I'd rather see that unusual variation named something unusual.

[Deprecated (see juliatuttle), 2016/03/16 16:45:30]

Done.

+    base::TimeDelta* out) {
+  std::string group = base::FieldTrialList::FindFullName(field_trial);
+  std::vector<base::StringPiece> group_parts = base::SplitStringPiece(
+      group, ":", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
+  if (type_int < 0)
+    return false;
+  size_t type = static_cast<size_t>(type_int);
+  if (type >= group_parts.size())
+    return false;

[Randy Smith (Not in Mondays), 2016/03/15 20:12:30]

Will this catch the case when the field trial isn't set at all?  I'd expect
(haven't checked) group to be the null string in that case, and I'd expect
(haven't checked) SplitStringPiece to return a single entry, so I'd expect a
type of 0 to work when it shoudln't.

[Deprecated (see juliatuttle), 2016/03/16 16:45:30]

Technically, I think StringToInt64 would then fail, but I don't think that's a
proper way to handle it. I'll add a specific check on group at the top.

+  int64_t ms;
+  if (!base::StringToInt64(group_parts[type], &ms))
+    return false;
+  *out = base::TimeDelta::FromMilliseconds(ms);
+  return true;
+}
+
+}  // namespace
+
+base::TimeDelta GetTimeDeltaForConnectionTypeFromFieldTrialOrDefault(
+    const char* field_trial,
+    base::TimeDelta default_delta,
+    NetworkChangeNotifier::ConnectionType type) {
+  base::TimeDelta out;
+  if (!GetTimeDeltaForConnectionTypeFromFieldTrial(field_trial, type, &out))
+    out = default_delta;
+  return out;
+}
+#endif  // !defined(OS_NACL)
+
 }  // namespace net