Introduce a MetricsDataProvider interface.

chrome/browser/metrics/metrics_log.h

Index: chrome/browser/metrics/metrics_log.h
===================================================================
--- chrome/browser/metrics/metrics_log.h	(revision 271296)
+++ chrome/browser/metrics/metrics_log.h	(working copy)
@@ -12,6 +12,7 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/memory/scoped_vector.h"
 #include "chrome/browser/metrics/extension_metrics.h"
 #include "chrome/browser/metrics/metrics_network_observer.h"
 #include "chrome/common/metrics/variations/variations_util.h"
@@ -37,6 +38,10 @@
 struct WebPluginInfo;
 }
 
+namespace metrics {
+class MetricsDataProvider;
+}
+
 namespace tracked_objects {
 struct ProcessDataSnapshot;
 }
@@ -89,6 +94,7 @@
   // example, a pref may be mapped to a synthetic trial such that the group
   // is determined by the pref value.
   void RecordEnvironment(
+      const ScopedVector<metrics::MetricsDataProvider>& data_providers,

[Ilya Sherman, 2014/05/19 14:45:00]

nit: Passing ScopedVectors is a little odd.  Please pass the underlying
std::vector instead.  (Ditto throughout.)

[Ilya Sherman, 2014/05/19 14:45:00]

nit: Please update the docs.

[Alexei Svitkine (slow), 2014/05/19 15:23:02]

Didn't realise it's possible to access the underlying vector. Done.

[Alexei Svitkine (slow), 2014/05/19 15:23:02]

Done.

       const std::vector<content::WebPluginInfo>& plugin_list,
       const GoogleUpdateMetrics& google_update_metrics,
       const std::vector<chrome_variations::ActiveGroupId>& synthetic_trials);
@@ -116,9 +122,15 @@
   // If this log is of type INITIAL_STABILITY_LOG, records additional info such
   // as number of incomplete shutdowns as well as extra breakpad and debugger
   // stats.
-  void RecordStabilityMetrics(base::TimeDelta incremental_uptime,
-                              base::TimeDelta uptime);
+  void RecordStabilityMetrics(
+      const ScopedVector<metrics::MetricsDataProvider>& data_providers,

[Ilya Sherman, 2014/05/19 14:45:00]

nit: Please update the docs.

[Alexei Svitkine (slow), 2014/05/19 15:23:02]

Done.

+      base::TimeDelta incremental_uptime,
+      base::TimeDelta uptime);
 
+  // Record general metrics based on the specified |providers|.
+  void RecordGeneralMetrics(
+      const ScopedVector<metrics::MetricsDataProvider>& data_providers);
+
   const base::TimeTicks& creation_time() const {
     return creation_time_;
   }