[MD History] Add UMA stats for switching views and the CBD button.

chrome/browser/resources/md_history/browser_service.js

Index: chrome/browser/resources/md_history/browser_service.js
diff --git a/chrome/browser/resources/md_history/browser_service.js b/chrome/browser/resources/md_history/browser_service.js
index 02fc3590ef530ffd7652b021da8269f6e6a50881..357554de149fa41aa911d21ed0358a0d33148128 100644
--- a/chrome/browser/resources/md_history/browser_service.js
+++ b/chrome/browser/resources/md_history/browser_service.js
@@ -81,6 +81,15 @@ cr.define('md_history', function() {
     },
 
     /**
+     * @param {string} histogram
+     * @param {number} value
+     * @param {number} max
+     */
+    recordHistogram: function(histogram, value, max) {
+      chrome.send('metricsHandler:recordInHistogram', [histogram, value, max]);
+    },
+
+    /**
     * Record an action in UMA.
     * @param {string} actionDesc The name of the action to be logged.
     */