Add UMA histogram data representing the Synced Notifications feature.

chrome/browser/notifications/sync_notifier/chrome_notifier_delegate.h

Index: chrome/browser/notifications/sync_notifier/chrome_notifier_delegate.h
diff --git a/chrome/browser/notifications/sync_notifier/chrome_notifier_delegate.h b/chrome/browser/notifications/sync_notifier/chrome_notifier_delegate.h
index f0ea79bac5ba85226b3c5c8351005924fff61b02..4bf75fedf9f45c130c1946a40147b6c97065ba58 100644
--- a/chrome/browser/notifications/sync_notifier/chrome_notifier_delegate.h
+++ b/chrome/browser/notifications/sync_notifier/chrome_notifier_delegate.h
@@ -5,6 +5,7 @@
 #ifndef CHROME_BROWSER_NOTIFICATIONS_SYNC_NOTIFIER_CHROME_NOTIFIER_DELEGATE_H_
 #define CHROME_BROWSER_NOTIFICATIONS_SYNC_NOTIFIER_CHROME_NOTIFIER_DELEGATE_H_
 
+#include <map>
 #include <string>
 
 #include "chrome/browser/notifications/notification_delegate.h"
@@ -12,6 +13,19 @@
 
 namespace notifier {
 
+enum SyncedNotificationActionType {
+  SYNCED_NOTIFICATION_ACTION_UNKNOWN,
+  SYNCED_NOTIFICATION_ACTION_CLICK,
+  SYNCED_NOTIFICATION_ACTION_BUTTON_CLICK,
+  SYNCED_NOTIFICATION_ACTION_CLOSE_BY_USER,
+  SYNCED_NOTIFICATION_ACTION_CLOSE_BY_SYSTEM,
+  SYNCED_NOTIFICATION_ACTION_TOAST_TIMEOUT,
+  // NOTE: Add new action types only immediately above this line. Also,
+  // make sure the enum list in tools/histogram/histograms.xml is
+  // updated with any change in here.
+  SYNCED_NOTIFICATION_ACTION_COUNT
+};
+
 class ChromeNotifierService;
 
 // ChromeNotifierDelegate is a NotificationDelegate which catches
@@ -35,6 +49,8 @@ class ChromeNotifierDelegate : public NotificationDelegate {
 
   virtual content::RenderViewHost* GetRenderViewHost() const OVERRIDE;
 
+  void CollectAction(SyncedNotificationActionType type);
+
  private:
   virtual ~ChromeNotifierDelegate();
   void NavigateToUrl(const GURL& destination) const;