Getting answer server URL from the variations server.

ui/app_list/app_list_switches.cc

Index: ui/app_list/app_list_switches.cc
diff --git a/ui/app_list/app_list_switches.cc b/ui/app_list/app_list_switches.cc
index c583832888b98b9b0fdb8fb5893c7dc800f2dd4e..ee18cd65e46e58432219560c3ffdc91cd2fb2fe3 100644
--- a/ui/app_list/app_list_switches.cc
+++ b/ui/app_list/app_list_switches.cc
@@ -5,6 +5,7 @@
 #include "ui/app_list/app_list_switches.h"
 
 #include "base/command_line.h"
+#include "base/metrics/field_trial_params.h"
 #include "build/build_config.h"
 
 namespace app_list {
@@ -79,12 +80,19 @@ bool IsDriveSearchInChromeLauncherEnabled() {
 }
 
 std::string AnswerServerUrl() {
-  return base::CommandLine::ForCurrentProcess()->GetSwitchValueNative(
-      kAnswerServerUrl);
+  // If the answer server URL is passed in the command line, use it, otherwise
+  // get it from the variations server.
+  std::string variations_url = base::GetFieldTrialParamValue(

[xiyuan, 2017/04/26 23:18:00]

nit: get rid of |variations_url| and inline GetFieldTrialParamValue. So that we
only call it when there is no command line switch.

[vadimt, 2017/04/26 23:29:42]

See the links I'll send. Quote:

  // Note: It's important to query the field trial state first, to ensure that
  // UMA reports the correct group.

+      "SearchAnswerCard", switches::kAnswerServerUrl);
+  std::string url =

[xiyuan, 2017/04/26 23:18:00]

nit: const

[vadimt, 2017/04/26 23:29:42]

Done.
I like consts, but I'm not using them in Chrome since this doesn't seem to be a
common practice. I don't want my style to deviate from the average.

+      base::CommandLine::ForCurrentProcess()->GetSwitchValueNative(
+          kAnswerServerUrl);
+  return !url.empty() ? url : variations_url;
 }
 
 bool IsAnswerCardEnabled() {
-  return !AnswerServerUrl().empty();
+  static const bool enabled = !AnswerServerUrl().empty();
+  return enabled;
 }
 
 }  // namespace switches