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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 /**
      6  * @fileoverview Utility methods for accessing chrome.metricsPrivate API.
      7  *
      8  * To be included as a first script in main.html
      9  */
     10 
     11 var metrics = {};
     12 
     13 /**
     14  * A map from interval name to interval start timestamp.
     15  */
     16 metrics.intervals = {};
     17 
     18 /**
     19  * Start the named time interval.
     20  * Should be followed by a call to recordInterval with the same name.
     21  *
     22  * @param {string} name Unique interval name.
     23  */
     24 metrics.startInterval = function(name) {
     25   metrics.intervals[name] = Date.now();
     26 };
     27 
     28 metrics.startInterval('Load.Total');
     29 metrics.startInterval('Load.Script');
     30 
     31 /**
     32  * Convert a short metric name to the full format.
     33  *
     34  * @param {string} name Short metric name.
     35  * @return {string} Full metric name.
     36  * @private
     37  */
     38 metrics.convertName_ = function(name) {
     39   return 'FileBrowser.' + name;
     40 };
     41 
     42 /**
     43  * Wrapper method for calling chrome.fileBrowserPrivate safely.
     44  * @param {string} name Method name.
     45  * @param {Array.<Object>} args Arguments.
     46  * @private
     47  */
     48 metrics.call_ = function(name, args) {
     49   try {
     50     chrome.metricsPrivate[name].apply(chrome.metricsPrivate, args);
     51   } catch (e) {
     52     console.error(e.stack);
     53   }
     54 };
     55 
     56 /**
     57  * Create a decorator function that calls a chrome.metricsPrivate function
     58  * with the same name and correct parameters.
     59  *
     60  * @param {string} name Method name.
     61  */
     62 metrics.decorate = function(name) {
     63   metrics[name] = function() {
     64     var args = Array.apply(null, arguments);
     65     args[0] = metrics.convertName_(args[0]);
     66     metrics.call_(name, args);
     67     if (metrics.log) {
     68       console.log('chrome.metricsPrivate.' + name, args);
     69     }
     70   };
     71 };
     72 
     73 metrics.decorate('recordMediumCount');
     74 metrics.decorate('recordSmallCount');
     75 metrics.decorate('recordTime');
     76 metrics.decorate('recordUserAction');
     77 
     78 /**
     79  * Complete the time interval recording.
     80  *
     81  * Should be preceded by a call to startInterval with the same name. *
     82  *
     83  * @param {string} name Unique interval name.
     84  */
     85 metrics.recordInterval = function(name) {
     86   if (name in metrics.intervals) {
     87     metrics.recordTime(name, Date.now() - metrics.intervals[name]);
     88   } else {
     89     console.error('Unknown interval: ' + name);
     90   }
     91 };
     92 
     93 /**
     94  * Record an enum value.
     95  *
     96  * @param {string} name Metric name.
     97  * @param {Object} value Enum value.
     98  * @param {Array.<Object>|number} validValues Array of valid values
     99  *                                            or a boundary number value.
    100  */
    101 metrics.recordEnum = function(name, value, validValues) {
    102   var boundaryValue;
    103   var index;
    104   if (validValues.constructor.name == 'Array') {
    105     index = validValues.indexOf(value);
    106     boundaryValue = validValues.length;
    107   } else {
    108     index = value;
    109     boundaryValue = validValues;
    110   }
    111   // Collect invalid values in the overflow bucket at the end.
    112   if (index < 0 || index > boundaryValue)
    113     index = boundaryValue;
    114 
    115   // Setting min to 1 looks strange but this is exactly the recommended way
    116   // of using histograms for enum-like types. Bucket #0 works as a regular
    117   // bucket AND the underflow bucket.
    118   // (Source: UMA_HISTOGRAM_ENUMERATION definition in base/metrics/histogram.h)
    119   var metricDescr = {
    120     'metricName': metrics.convertName_(name),
    121     'type': 'histogram-linear',
    122     'min': 1,
    123     'max': boundaryValue,
    124     'buckets': boundaryValue + 1
    125   };
    126   metrics.call_('recordValue', [metricDescr, index]);
    127   if (metrics.log) {
    128     console.log('chrome.metricsPrivate.recordValue',
    129         [metricDescr.metricName, index, value]);
    130   }
    131 };
    132