content: convert user action notification to observer usage

content/browser/user_metrics.cc

Index: content/browser/user_metrics.cc
diff --git a/content/browser/user_metrics.cc b/content/browser/user_metrics.cc
index 927f3977d6b589f3363ca1c3d9b4a594d48c36ff..a1c7819a5443cae5b22aad918ce3051b06d06b7d 100644
--- a/content/browser/user_metrics.cc
+++ b/content/browser/user_metrics.cc
@@ -4,14 +4,18 @@
 
 #include "content/public/browser/user_metrics.h"
 
+#include <vector>
+
 #include "base/bind.h"
+#include "base/lazy_instance.h"
 #include "content/public/browser/browser_thread.h"
-#include "content/public/browser/notification_service.h"
-#include "content/public/browser/notification_types.h"
 
 namespace content {
 namespace {
 
+base::LazyInstance<std::vector<ActionCallback> > g_action_callbacks =
+    LAZY_INSTANCE_INITIALIZER;
+
 // Forward declare because of circular dependency.
 void CallRecordOnUI(const std::string& action);
 
@@ -24,10 +28,8 @@ void Record(const char *action) {
     return;
   }
 
-  NotificationService::current()->Notify(
-      NOTIFICATION_USER_ACTION,
-      NotificationService::AllSources(),
-      Details<const char*>(&action));
+  for (size_t i = 0; i < g_action_callbacks.Get().size(); i++)
+    g_action_callbacks.Get()[i].Run(action);
 }
 
 void CallRecordOnUI(const std::string& action) {
@@ -44,4 +46,17 @@ void RecordComputedAction(const std::string& action) {
   Record(action.c_str());
 }
 
+void AddActionCallback(const ActionCallback& callback) {
+  g_action_callbacks.Get().push_back(callback);
+}
+
+void RemoveActionCallback(const ActionCallback& callback) {
+  for (size_t i = 0; i < g_action_callbacks.Get().size(); i++) {
+    if (g_action_callbacks.Get()[i].Equals(callback)) {
+      g_action_callbacks.Get().erase(g_action_callbacks.Get().begin() + i);
+      return;
+    }
+  }
+}
+
 }  // namespace content