Add an IPC method for Blink to call RapporService::RecordSample()

base/metrics/user_metrics.cc

Index: base/metrics/user_metrics.cc
diff --git a/base/metrics/user_metrics.cc b/base/metrics/user_metrics.cc
index 9db5840ab57052746537bb223a8f6445735d53d9..ee02893f19e2edd4de3c588ba7b0a526360721ea 100644
--- a/base/metrics/user_metrics.cc
+++ b/base/metrics/user_metrics.cc
@@ -25,6 +25,12 @@ class Callbacks {
     }
   }
 
+  void Record(const std::string& metric, const std::string& sample) {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    if (!rappor_callback_.is_null())
+      rappor_callback_.Run(metric, sample);
+  }
+
   // Adds |callback| to the list of |callbacks_|.
   void AddCallback(const ActionCallback& callback) {
     DCHECK(thread_checker_.CalledOnValidThread());
@@ -43,9 +49,16 @@ class Callbacks {
     }
   }
 
+  void AddCallback(const RapporCallback& callback) {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    DCHECK(rappor_callback_.is_null());
+    rappor_callback_ = callback;
+  }
+
  private:
   base::ThreadChecker thread_checker_;
   std::vector<ActionCallback> callbacks_;
+  RapporCallback rappor_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(Callbacks);
 };
@@ -62,13 +75,20 @@ void RecordComputedAction(const std::string& action) {
   g_callbacks.Get().Record(action);
 }
 
+void RecordRappor(const std::string& metric, const std::string& sample) {
+  g_callbacks.Get().Record(metric, sample);
+}
+
 void AddActionCallback(const ActionCallback& callback) {
   g_callbacks.Get().AddCallback(callback);
 }
 
 void RemoveActionCallback(const ActionCallback& callback) {
   g_callbacks.Get().RemoveCallback(callback);
+}
 
+void AddRapporCallback(const RapporCallback& callback) {
+  g_callbacks.Get().AddCallback(callback);
 }
 
 }  // namespace base