Backed out changeset ef75e158b232 (bug 1556000) for bc failures on browser_startup_syncIPC.js

browser/base/content/browser.js

@@ -1959,6 +1959,26 @@ var gBrowserInit = {
       scheduleIdleTask(() => Win7Features.onOpenWindow());
     }
 
+    scheduleIdleTask(() => {
+      if (Services.prefs.getBoolPref("privacy.resistFingerprinting")) {
+        return;
+      }
+
+      setTimeout(() => {
+        if (window.closed) {
+          return;
+        }
+
+        let browser = gBrowser.selectedBrowser;
+        let browserBounds = window.windowUtils.getBoundsWithoutFlushing(browser);
+
+        Services.telemetry.keyedScalarAdd(
+          "resistfingerprinting.content_window_size",
+          `${browserBounds.width}x${browserBounds.height}`,
+          1);
+      }, 300 * 1000);
+    });
+
     scheduleIdleTask(async () => {
       NewTabPagePreloading.maybeCreatePreloadedBrowser(window);
     });

toolkit/components/telemetry/Scalars.yaml

@@ -2719,6 +2719,23 @@ memoryreporter:
     record_in_processes:
       - 'content'
 
+resistfingerprinting:
+  content_window_size:
+    bug_numbers:
+      - 1489493
+    description: >
+      The size (in pixels) of the content windows for innerWidth and innerHeight.
+    expires: "66"
+    kind: uint
+    keyed: true
+    notification_emails:
+      - tihuang@mozilla.com
+      - tom@mozilla.com
+      - ettseng@mozilla.com
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
 update:
   binarytransparencyresult:
     bug_numbers: