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

base/metrics/user_metrics.h

Index: base/metrics/user_metrics.h
diff --git a/base/metrics/user_metrics.h b/base/metrics/user_metrics.h
index bcfefb809942e203590dfd9db7672cc56f861c7c..79b84c424afe1c87e3c97e746ca08efdaa207841 100644
--- a/base/metrics/user_metrics.h
+++ b/base/metrics/user_metrics.h
@@ -48,6 +48,11 @@ BASE_EXPORT void RecordAction(const UserMetricsAction& action);
 // tools/metrics/actions/extract_actions.py.
 BASE_EXPORT void RecordComputedAction(const std::string& action);
 
+// This function records a sample string along with the metric using RAPPOR.
+BASE_EXPORT void RecordRappor(
+    const std::string& metric,
+    const std::string& sample);

[Ilya Sherman, 2015/03/25 20:51:02]

RAPPOR is not a concept that current exists in base.  I'm not really convinced
that it's appropriate to add it here.  But, if we do decide that //base is the
right place to add it, please create a new file for it.  The user_metrics files
are for user actions, not for all UMA metrics.  (I do realize that the name is
somewhat confusing :/)

+
 // Called with the action string.
 typedef base::Callback<void(const std::string&)> ActionCallback;
 
@@ -55,6 +60,12 @@ typedef base::Callback<void(const std::string&)> ActionCallback;
 BASE_EXPORT void AddActionCallback(const ActionCallback& callback);
 BASE_EXPORT void RemoveActionCallback(const ActionCallback& callback);
 
+typedef base::Callback<void(
+    const std::string&,
+    const std::string&)> RapporCallback;
+
+BASE_EXPORT void AddRapporCallback(const RapporCallback& callback);
+
 }  // namespace base
 
 #endif  // BASE_METRICS_USER_METRICS_H_