From 9defcbd8777d06c1b498f94d102fc25db3d6bb40 Mon Sep 17 00:00:00 2001
From: Justin Dolske <dolske@mozilla.com>
Date: Fri, 27 Jun 2014 11:20:02 -0700
Subject: [PATCH] Bug 1023508 - Add telemetry for HiDPI usage. r=felipe

---
 browser/components/nsBrowserGlue.js          | 18 +++++++++++++++
 toolkit/components/telemetry/Histograms.json | 24 ++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/browser/components/nsBrowserGlue.js b/browser/components/nsBrowserGlue.js
index da9fcad6ab8f..574a6933c164 100644
--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -630,6 +630,22 @@ BrowserGlue.prototype = {
                           nb.PRIORITY_INFO_LOW, buttons);
   },
 
+  _firstWindowTelemetry: function(aWindow) {
+#ifdef XP_WIN
+    let SCALING_PROBE_NAME = "DISPLAY_SCALING_MSWIN";
+#elifdef XP_MACOSX
+    let SCALING_PROBE_NAME = "DISPLAY_SCALING_OSX";
+#elifdef XP_LINUX
+    let SCALING_PROBE_NAME = "DISPLAY_SCALING_LINUX";
+#else
+    let SCALING_PROBE_NAME = "";
+#endif
+    if (SCALING_PROBE_NAME) {
+      let scaling = aWindow.devicePixelRatio * 100;
+      Services.telemetry.getHistogramById(SCALING_PROBE_NAME).add(scaling);
+    }
+  },
+
   // the first browser window has finished initializing
   _onFirstWindowLoaded: function BG__onFirstWindowLoaded(aWindow) {
 #ifdef XP_WIN
@@ -658,6 +674,8 @@ BrowserGlue.prototype = {
     }
 
     this._checkForOldBuildUpdates();
+
+    this._firstWindowTelemetry(aWindow);
   },
 
   /**
diff --git a/toolkit/components/telemetry/Histograms.json b/toolkit/components/telemetry/Histograms.json
index 1297ffce4aa4..2ab5b57efe7b 100644
--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -6446,5 +6446,29 @@
     "expires_in_version": "never",
     "kind": "flag",
     "description": "If a master-password is enabled for this profile"
+  },
+  "DISPLAY_SCALING_OSX" : {
+    "expires_in_version": "never",
+    "kind": "linear",
+    "high": "500",
+    "n_buckets": "100",
+    "description": "Scaling percentage for the display where the first window is opened (OS X only)",
+    "cpp_guard": "XP_MACOSX"
+  },
+  "DISPLAY_SCALING_MSWIN" : {
+    "expires_in_version": "never",
+    "kind": "linear",
+    "high": "500",
+    "n_buckets": "100",
+    "description": "Scaling percentage for the display where the first window is opened (MS Windows only)",
+    "cpp_guard": "XP_WIN"
+  },
+  "DISPLAY_SCALING_LINUX" : {
+    "expires_in_version": "never",
+    "kind": "linear",
+    "high": "500",
+    "n_buckets": "100",
+    "description": "Scaling percentage for the display where the first window is opened (Linux only)",
+    "cpp_guard": "XP_LINUX"
   }
 }