Bug 1396811 - Add new telemetry probe collecting the current theme; r=chutten,liuche,ochameau

MozReview-Commit-ID: KlUHlc7YEx9

--HG--
extra : rebase_source : 8ae8fc1458a57d60a45869dc2c4796cae63dc7f3

devtools/client/framework/toolbox.js

@@ -12,6 +12,7 @@ const SPLITCONSOLE_HEIGHT_PREF = "devtools.toolbox.splitconsoleHeight";
 const DISABLE_AUTOHIDE_PREF = "ui.popup.disable_autohide";
 const HOST_HISTOGRAM = "DEVTOOLS_TOOLBOX_HOST";
 const SCREENSIZE_HISTOGRAM = "DEVTOOLS_SCREEN_RESOLUTION_ENUMERATED_PER_USER";
+const CURRENT_THEME_SCALAR = "devtools.current_theme";
 const HTML_NS = "http://www.w3.org/1999/xhtml";
 
 var {Ci, Cu, Cc} = require("chrome");
@@ -650,6 +651,11 @@ Toolbox.prototype = {
     this._telemetry.logOncePerBrowserVersion(SCREENSIZE_HISTOGRAM,
                                              system.getScreenDimensions());
     this._telemetry.log(HOST_HISTOGRAM, this._getTelemetryHostId());
+
+    // Log current theme. The question we want to answer is:
+    // "What proportion of users use which themes?"
+    let currentTheme = Services.prefs.getCharPref("devtools.theme");
+    this._telemetry.logKeyedScalar(CURRENT_THEME_SCALAR, currentTheme, 1);
   },
 
   /**

devtools/client/shared/telemetry.js

@@ -17,6 +17,8 @@ function Telemetry() {
   this.toolOpened = this.toolOpened.bind(this);
   this.toolClosed = this.toolClosed.bind(this);
   this.log = this.log.bind(this);
+  this.logScalar = this.logScalar.bind(this);
+  this.logKeyedScalar = this.logKeyedScalar.bind(this);
   this.logOncePerBrowserVersion = this.logOncePerBrowserVersion.bind(this);
   this.destroy = this.destroy.bind(this);
 
@@ -309,6 +311,36 @@ Telemetry.prototype = {
     }
   },
 
+  /**
+   * Log a value to a keyed count scalar.
+   *
+   * @param  {String} scalarId
+   *         Scalar in which the data is to be stored.
+   * @param  {String} key
+   *         The key within the  scalar.
+   * @param  value
+   *         Value to store.
+   */
+  logKeyedScalar: function (scalarId, key, value) {
+    if (!scalarId) {
+      return;
+    }
+
+    try {
+      if (isNaN(value)) {
+        dump(`Warning: An attempt was made to write a non-numeric value ` +
+             `${value} to the ${scalarId} scalar. Only numeric values are ` +
+             `allowed.`);
+
+        return;
+      }
+      Services.telemetry.keyedScalarAdd(scalarId, key, value);
+    } catch (e) {
+      dump(`Warning: An attempt was made to write to the ${scalarId} ` +
+           `scalar, which is not defined in Scalars.yaml\n`);
+    }
+  },
+
   /**
    * Log a value to a keyed histogram.
    *

toolkit/components/telemetry/Scalars.yaml

@@ -775,6 +775,21 @@ devtools.grid.showInfiniteLines:
     record_in_processes:
       - 'main'
 
+devtools:
+  current_theme:
+    bug_numbers:
+      - 1396811
+    description: >
+      Number of times DevTools was opened, keyed by theme.
+    expires: never
+    kind: uint
+    keyed: true
+    notification_emails:
+      - dev-developer-tools@lists.mozilla.org
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
 navigator.storage:
   estimate_count:
     bug_numbers: