content: convert user action notification to observer usage

chrome/browser/metrics/metrics_service.h

Index: chrome/browser/metrics/metrics_service.h
diff --git a/chrome/browser/metrics/metrics_service.h b/chrome/browser/metrics/metrics_service.h
index 308fe57ba1db9653251effc95e3bf085f6b34f16..83475a57efdbd32322ab059497b0acadab5100d1 100644
--- a/chrome/browser/metrics/metrics_service.h
+++ b/chrome/browser/metrics/metrics_service.h
@@ -24,6 +24,7 @@
 #include "chrome/installer/util/google_update_settings.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/user_metrics.h"
 #include "net/url_request/url_fetcher_delegate.h"
 
 #if defined(OS_CHROMEOS)
@@ -236,6 +237,8 @@ class MetricsService
   void OnInitTaskGotGoogleUpdateData(
       const GoogleUpdateMetrics& google_update_metrics);
 
+  void OnUserAction(const std::string& action);
+
   // TrackingSynchronizerObserver:
   virtual void ReceivedProfilerData(
       const tracked_objects::ProcessDataSnapshot& process_data,
@@ -398,9 +401,7 @@ class MetricsService
                        const content::NotificationDetails& details);
 
   // Checks whether a notification can be logged.
-  bool CanLogNotification(int type,
-                          const content::NotificationSource& source,
-                          const content::NotificationDetails& details);
+  bool CanLogNotification();
 
   // Sets the value of the specified path in prefs and schedules a save.
   void RecordBooleanPrefValue(const char* path, bool value);
@@ -409,6 +410,8 @@ class MetricsService
   // process, and false otherwise.
   static bool IsPluginProcess(content::ProcessType type);
 
+  content::ActionCallback action_callback_;
+
   content::NotificationRegistrar registrar_;
 
   // Indicate whether recording and reporting are currently happening.