Enable captive portal detection by default.

chrome/browser/captive_portal/captive_portal_service.cc

Index: chrome/browser/captive_portal/captive_portal_service.cc
===================================================================
--- chrome/browser/captive_portal/captive_portal_service.cc	(revision 147935)
+++ chrome/browser/captive_portal/captive_portal_service.cc	(working copy)
@@ -326,9 +326,21 @@
 
 void CaptivePortalService::UpdateEnabledState() {
   bool enabled_before = enabled_;
-  enabled_ = resolve_errors_with_web_service_.GetValue() &&
-             CommandLine::ForCurrentProcess()->HasSwitch(
-                 switches::kCaptivePortalDetection);
+
+  // Default value.
+  bool allowed_by_command_line = true;
+
+  std::string command_line_value =
+      CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          switches::kCaptivePortalDetection);
+  if (command_line_value == switches::kCaptivePortalDetectionDisabled) {
+    allowed_by_command_line = false;
+  } else if (command_line_value == switches::kCaptivePortalDetectionEnabled) {
+    allowed_by_command_line = true;
+  }
+
+  enabled_ = allowed_by_command_line &&
+             resolve_errors_with_web_service_.GetValue();
   if (enabled_before == enabled_)
     return;