Add metrics for Webstore Gallery Widget app

components/chrome_apps/webstore_widget/app/main.js

Index: components/chrome_apps/webstore_widget/app/main.js
diff --git a/components/chrome_apps/webstore_widget/app/main.js b/components/chrome_apps/webstore_widget/app/main.js
index 1151da84a367588a199a5f6da0440fa529f86c89..f0ca4676ec4f5ea5420921b248ecb6dc6cf4ac8c 100644
--- a/components/chrome_apps/webstore_widget/app/main.js
+++ b/components/chrome_apps/webstore_widget/app/main.js
@@ -68,20 +68,50 @@ function createPlatformDelegate(strings) {
 
     metricsImpl: {
       /**
+       * Map from interval name to interval start timestamp.
+       * @type {Object<string, Date>}
+       */
+      intervals: {},
+
+      /**
        * @param {string} enumName
        * @param {number} value
        * @param {number} enumSize
        */
-      recordEnum: function(enumName, value, enumSize) {},
+      recordEnum: function(enumName, value, enumSize) {
+        var index = (value >= 0 && value < enumSize) ? value : enumSize;
+        chrome.metricsPrivate.recordValue({
+          'metricName': 'WebstoreWidgetApp.' + enumName,
+          'type': 'histogram-linear',
+          'min': 1,
+          'max': enumSize,
+          'buckets': enumSize + 1
+        }, index);
+      },
 
       /** @param {string} actionName */
-      recordUserAction: function(actionName) {},
+      recordUserAction: function(actionName) {
+        chrome.metricsPrivate.recordUserAction(
+            'WebstoreWidgetApp.' + actionName);
+      },
 
       /** @param {string} intervalName */
-      startInterval: function(intervalName) {},
+      startInterval: function(intervalName) {
+        this.intervals[intervalName] = Date.now();
+      },
 
       /** @param {string} intervalName */
-      recordInterval: function(intervalName) {}
+      recordInterval: function(intervalName) {
+        if (!intervalName in this.intervals) {
+          console.error('Interval \'' + intervalName + '\' not started');
+          return;
+        }
+
+       chrome.metricsPrivate.recordTime(
+           'WebstoreWidgetApp.' + intervalName,
+           Date.now() - this.intervals[intervalName]);
+        delete this.intervals[intervalName];
+      }
     },
 
     /**