Add metrics for interactions with the Apps Launcher promo dialog.

chrome/browser/ui/webui/ntp/app_launcher_handler.cc

Index: chrome/browser/ui/webui/ntp/app_launcher_handler.cc
diff --git a/chrome/browser/ui/webui/ntp/app_launcher_handler.cc b/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
index 88bff10639a3216ebdf90b828ba72f740a440b0c..7ce8c0634a1700ad0b0d8667a6360724c82f5f2a 100644
--- a/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
+++ b/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
@@ -6,6 +6,7 @@
 
 #include <vector>
 
+#include "apps/metrics_names.h"
 #include "apps/pref_names.h"
 #include "base/auto_reset.h"
 #include "base/bind.h"
@@ -212,6 +213,9 @@ void AppLauncherHandler::RegisterMessages() {
   web_ui()->RegisterMessageCallback("stopShowingAppLauncherPromo",
       base::Bind(&AppLauncherHandler::StopShowingAppLauncherPromo,
                  base::Unretained(this)));
+  web_ui()->RegisterMessageCallback("onLearnMore",
+      base::Bind(&AppLauncherHandler::OnLearnMore,
+                 base::Unretained(this)));
 }
 
 void AppLauncherHandler::Observe(int type,
@@ -694,6 +698,11 @@ void AppLauncherHandler::StopShowingAppLauncherPromo(
     const base::ListValue* args) {
   g_browser_process->local_state()->SetBoolean(
       apps::prefs::kShowAppLauncherPromo, false);
+  RecordAppLauncherPromoHistogram(apps::APP_LAUNCHER_PROMO_DISMISSED);
+}
+
+void AppLauncherHandler::OnLearnMore(const base::ListValue* args) {
+  RecordAppLauncherPromoHistogram(apps::APP_LAUNCHER_PROMO_LEARN_MORE);
 }
 
 void AppLauncherHandler::OnFaviconForApp(
@@ -790,6 +799,14 @@ void AppLauncherHandler::RecordAppListMainLaunch(const Extension* extension) {
 }
 
 // static
+void AppLauncherHandler::RecordAppLauncherPromoHistogram(
+      apps::AppLauncherPromoHistogramValues histogram) {

[Ilya Sherman, 2013/06/26 22:19:49]

nit: Please add a DCHECK() verifying that the argument is less than
APP_LAUNCHER_PROMO_MAX.

[MAD, 2013/06/27 21:43:35]

Done.

+  UMA_HISTOGRAM_ENUMERATION(apps::kAppLauncherPromoHistogram,
+                            histogram,
+                            apps::APP_LAUNCHER_PROMO_MAX);
+}
+
+// static
 void AppLauncherHandler::RecordWebStoreLaunch() {
   RecordAppLaunchType(extension_misc::APP_LAUNCH_NTP_WEBSTORE,
       extensions::Manifest::TYPE_HOSTED_APP);