Add a private API method metricsPrivate.getFieldTrial(), which returns

the group for field trial experiment. Equivalent to
FieldTrialList::FindFullName().

Review URL: https://chromiumcodereview.appspot.com/17496005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@208101 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/extensions/api/metrics_private/metrics_apitest.cc

@@ -4,6 +4,7 @@
 
 #include <map>
 
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/statistics_recorder.h"
 #include "chrome/browser/extensions/extension_apitest.h"
@@ -126,6 +127,8 @@ void ValidateHistograms(const RecordedHistogram* recorded,
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, Metrics) {
   UserActionObserver observer;
 
+  base::FieldTrialList::CreateTrialsFromString("apitestfieldtrial2/group1/");
+
   ASSERT_TRUE(RunComponentExtensionTest("metrics")) << message_;
 
   observer.ValidateUserActions(g_user_actions, arraysize(g_user_actions));

chrome/browser/extensions/api/metrics_private/metrics_private_api.cc

@@ -6,6 +6,7 @@
 
 #include <algorithm>
 
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/browser_process.h"
@@ -22,6 +23,7 @@ namespace extensions {
 
 namespace GetIsCrashReportingEnabled =
     api::metrics_private::GetIsCrashReportingEnabled;
+namespace GetFieldTrial = api::metrics_private::GetFieldTrial;
 namespace RecordUserAction = api::metrics_private::RecordUserAction;
 namespace RecordValue = api::metrics_private::RecordValue;
 namespace RecordPercentage = api::metrics_private::RecordPercentage;
@@ -66,6 +68,14 @@ bool MetricsPrivateGetIsCrashReportingEnabledFunction::RunImpl() {
   return true;
 }
 
+bool MetricsPrivateGetFieldTrialFunction::RunImpl() {
+  std::string name;
+  EXTENSION_FUNCTION_VALIDATE(args_->GetString(0, &name));
+
+  SetResult(new base::StringValue(base::FieldTrialList::FindFullName(name)));
+  return true;
+}
+
 bool MetricsPrivateRecordUserActionFunction::RunImpl() {
   scoped_ptr<RecordUserAction::Params> params(
       RecordUserAction::Params::Create(*args_));

chrome/browser/extensions/api/metrics_private/metrics_private_api.h

@@ -25,6 +25,18 @@ class MetricsPrivateGetIsCrashReportingEnabledFunction
   virtual bool RunImpl() OVERRIDE;
 };
 
+class MetricsPrivateGetFieldTrialFunction : public SyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("metricsPrivate.getFieldTrial",
+                             METRICSPRIVATE_GETFIELDTRIAL)
+
+ protected:
+  virtual ~MetricsPrivateGetFieldTrialFunction() {}
+
+  // ExtensionFunction:
+  virtual bool RunImpl() OVERRIDE;
+};
+
 class MetricsPrivateRecordUserActionFunction : public SyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("metricsPrivate.recordUserAction",

chrome/browser/extensions/extension_function_histogram_value.h

@@ -554,6 +554,7 @@ enum HistogramValue {
   FEEDBACKPRIVATE_SENDFEEDBACK,
   EXPERIMENTAL_INPUT_VIRTUALKEYBOARD_INSERTTEXT,
   DIAGNOSTICS_SENDPACKET,
+  METRICSPRIVATE_GETFIELDTRIAL,
   ENUM_BOUNDARY // Last entry: Add new entries above.
 };
 

chrome/common/extensions/api/metrics_private.json

@@ -40,6 +40,22 @@
           }
         ]
       },
+      {
+        "name": "getFieldTrial",
+        "description": "Returns the group name chosen for the named trial, or the empty string if the trial does not exist or is not enabled.",
+        "type": "function",
+        "parameters": [
+          {"name": "name", "type": "string"},
+          {
+            "name": "callback",
+            "type": "function",
+            "optional": "false",
+            "parameters": [
+              { "name": "group", "type": "string" }
+            ]
+          }
+        ]
+      },
       {
         "name": "recordUserAction",
         "type": "function",

chrome/test/data/extensions/api_test/metrics/test.js

@@ -57,6 +57,20 @@ chrome.test.runTests([
     chrome.metricsPrivate.recordSmallCount('test.small.count', 42);
 
     chrome.test.succeed();
+  },
+
+  function getFieldTrial() {
+    var test1Callback = function(group) {
+      chrome.test.assertEq('', group);
+      chrome.metricsPrivate.getFieldTrial('apitestfieldtrial2', test2Callback);
+    };
+
+    var test2Callback = function(group) {
+      chrome.test.assertEq('group1', group);
+      chrome.test.succeed();
+    };
+
+    chrome.metricsPrivate.getFieldTrial('apitestfieldtrial1', test1Callback);
   }
 ]);