MetricsService API to support synthetic field trials

Extend the MetricsService API to register synthetic field trials, where trial groups map to Chrome configuration states, e.g., values of a preference. These trials are included in UMA reports.

BUG=270275

Review URL: https://codereview.chromium.org/22340005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234881 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 16 insertions, 6 deletions

diff --git a/chrome/browser/metrics/metrics_log.h b/chrome/browser/metrics/metrics_log.h
index fe4b11d..f00d49b 100644
--- a/chrome/browser/metrics/metrics_log.h
+++ b/chrome/browser/metrics/metrics_log.h
@@ -14,6 +14,7 @@
 #include "base/basictypes.h"
 #include "chrome/browser/metrics/metrics_network_observer.h"
 #include "chrome/common/metrics/metrics_log_base.h"
+#include "chrome/common/metrics/variations/variations_util.h"
 #include "chrome/installer/util/google_update_settings.h"
 #include "ui/gfx/size.h"
 
@@ -84,14 +85,15 @@ class MetricsLog : public MetricsLogBase {
   static const std::string& version_extension();
 
   // Records the current operating environment.  Takes the list of installed
-  // plugins and Google Update statistics as parameters because those can't be
-  // obtained synchronously from the UI thread.
-  // profile_metrics, if non-null, gives a dictionary of all profile metrics
-  // that are to be recorded. Each value in profile_metrics should be a
-  // dictionary giving the metrics for the profile.
+  // plugins, Google Update statistics, and synthetic trial IDs as parameters
+  // because those can't be obtained synchronously from the UI thread.
+  // A synthetic trial is one that is set up dynamically by code in Chrome. For
+  // example, a pref may be mapped to a synthetic trial such that the group
+  // is determined by the pref value.
   void RecordEnvironment(
       const std::vector<content::WebPluginInfo>& plugin_list,
       const GoogleUpdateMetrics& google_update_metrics,
+      const std::vector<chrome_variations::ActiveGroupId>& synthetic_trials,
       base::TimeDelta incremental_uptime);
 
   // Records the current operating environment.  Takes the list of installed
@@ -102,7 +104,8 @@ class MetricsLog : public MetricsLogBase {
   // upload.
   void RecordEnvironmentProto(
       const std::vector<content::WebPluginInfo>& plugin_list,
-      const GoogleUpdateMetrics& google_update_metrics);
+      const GoogleUpdateMetrics& google_update_metrics,
+      const std::vector<chrome_variations::ActiveGroupId>& synthetic_trials);
 
   // Records the input text, available choices, and selected entry when the
   // user uses the Omnibox to open a URL.
@@ -124,6 +127,10 @@ class MetricsLog : public MetricsLogBase {
       const std::vector<content::WebPluginInfo>& plugin_list,
       base::TimeDelta incremental_uptime);
 
+  const base::TimeTicks& creation_time() const {
+    return creation_time_;
+  }
+
  protected:
   // Exposed for the sake of mocking in test code.
 
@@ -201,6 +208,9 @@ class MetricsLog : public MetricsLogBase {
   // Bluetooth Adapter instance for collecting information about paired devices.
   scoped_refptr<device::BluetoothAdapter> adapter_;
 
+  // The time when the current log was created.
+  const base::TimeTicks creation_time_;
+
   DISALLOW_COPY_AND_ASSIGN(MetricsLog);
 };