Bug 1726465 - Don't update remote control cue for startup performance tests. r=florian

Startup performance tests are browser-chrome tests which use Marionette
to install required extensions. Because Marionette will be initialized
earlier during the startup of Firefox this can cause a partially updated
remote control cue for the first opened browser window.

As such stop updating the remote control cue by guarding this behavior
behind two flags - when the browser is in automation and a special
preference set.

Differential Revision: https://phabricator.services.mozilla.com/D145934

browser/base/content/browser.js

@@ -8403,6 +8403,16 @@ const gRemoteControl = {
   },
 
   updateVisualCue() {
+    // Disable updating the remote control cue for performance tests,
+    // because these could fail due to an early initialization of Marionette.
+    const disableRemoteControlCue = Services.prefs.getBoolPref(
+      "browser.chrome.disableRemoteControlCueForTests",
+      false
+    );
+    if (disableRemoteControlCue && Cu.isInAutomation) {
+      return;
+    }
+
     const mainWindow = document.documentElement;
     const remoteControlComponent = this.getRemoteControlComponent();
     if (remoteControlComponent) {

browser/base/content/test/performance/browser.ini

@@ -15,6 +15,9 @@ prefs =
   extensions.formautofill.addresses.available='on'
   extensions.formautofill.creditCards.available='on'
   browser.urlbar.disableExtendForTests=true
+  # For perfomance tests do not enable the remote control cue, which gets set
+  # when Marionette is enabled, but users normally don't see.
+  browser.chrome.disableRemoteControlCueForTests=true
   # The Screenshots extension is disabled by default in Mochitests. We re-enable
   # it here, since it's a more realistic configuration.
   extensions.screenshots.disabled=false