Bug 1624150 - Collect telemetry for outerWidth/outerHeight features of window.open in web content. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D67765

--HG--
extra : moz-landing-system : lando

toolkit/components/telemetry/Histograms.json

@@ -14949,6 +14949,16 @@
     "bug_numbers": [1597956, 1614905],
     "description": "milliseconds to complete a TLS session resumption with external cache"
   },
+  "WINDOW_OPEN_OUTER_SIZE": {
+    "record_in_processes": ["main", "content"],
+    "products": ["firefox"],
+    "alert_emails": ["tfujisawa.birchill@mozilla.com"],
+    "expires_in_version": "80",
+    "kind": "boolean",
+    "bug_numbers": [1624150],
+    "releaseChannelCollection": "opt-out",
+    "description": "Flag indicating consumer of non-standard outerWidth/outerHeight features in window.open"
+  },
   "WINDOW_REMOTE_SUBFRAMES_ENABLED_STATUS": {
     "record_in_processes": ["main"],
     "products": ["firefox"],

toolkit/components/windowwatcher/nsWindowWatcher.cpp

@@ -63,6 +63,7 @@
 #include "mozilla/ResultExtensions.h"
 #include "mozilla/StaticPrefs_fission.h"
 #include "mozilla/StaticPrefs_full_screen_api.h"
+#include "mozilla/Telemetry.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/Storage.h"
 #include "mozilla/dom/ScriptSettings.h"
@@ -684,6 +685,13 @@ nsresult nsWindowWatcher::OpenWindowInternal(
 
   bool isCallerChrome = nsContentUtils::LegacyIsCallerChromeOrNativeCode();
 
+  if (!hasChromeParent) {
+    bool outerSizeUsed =
+        features.Exists("outerwidth") || features.Exists("outerheight");
+    mozilla::Telemetry::Accumulate(mozilla::Telemetry::WINDOW_OPEN_OUTER_SIZE,
+                                   outerSizeUsed);
+  }
+
   SizeSpec sizeSpec;
   CalcSizeSpec(features, sizeSpec);