Add metrics for interactions with the Apps Launcher promo dialog.

apps/app_launcher.cc

Index: apps/app_launcher.cc
diff --git a/apps/app_launcher.cc b/apps/app_launcher.cc
index 0493c65aa4d8d30c530520fcd3531c31caf35b19..3f00b47a6cbeb8f36b9c72de1047e19cc5a8721d 100644
--- a/apps/app_launcher.cc
+++ b/apps/app_launcher.cc
@@ -4,7 +4,9 @@
 
 #include "apps/app_launcher.h"
 
+#include "apps/field_trial_names.h"
 #include "apps/pref_names.h"
+#include "base/metrics/field_trial.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/browser_process.h"
@@ -35,4 +37,18 @@ bool IsAppLauncherEnabled() {
 #endif
 }
 
+bool ShouldShowAppLauncherPromo() {
+  PrefService* local_state = g_browser_process->local_state();
+  // In some tests, the prefs aren't initialised.
+  if (!local_state)
+    return false;
+  std::string app_launcher_promo_group_name =
+      base::FieldTrialList::FindFullName(apps::kLauncherPromoTrialName);
+  return !IsAppLauncherEnabled() &&
+      local_state->GetBoolean(apps::prefs::kShowAppLauncherPromo) &&
+      (app_launcher_promo_group_name == apps::kShowLauncherPromoOnceGroupName ||
+       app_launcher_promo_group_name ==
+          apps::kResetShowLauncherPromoPrefGroupName);
+}
+
 }  // namespace apps