Bug 1694229 - Show slow script warning only when critical input is pending r=smaug

We want to restrict the slow script warning to cases where the user is actually
trying to interact with the browser.

Differential Revision: https://phabricator.services.mozilla.com/D106017

js/xpconnect/src/XPCJSContext.cpp

@@ -661,12 +661,10 @@ bool XPCJSContext::InterruptCallback(JSContext* cx) {
     return true;
   }
 
-  int32_t limitWithoutImportantUserInput =
-      StaticPrefs::dom_max_script_run_time_without_important_user_input();
-  if (runningContentJS && XRE_IsContentProcess() && limit &&
-      limitWithoutImportantUserInput > limit &&
-      limitWithoutImportantUserInput >
-          self->mSlowScriptActualWait.ToSeconds()) {
+  // For content scripts, we only want to show the slow script dialogue if the
+  // user is actually trying to perform an important interaction.
+  if (runningContentJS && XRE_IsContentProcess() &&
+      StaticPrefs::dom_max_script_run_time_require_critical_input()) {
     // Call possibly slow PeekMessages after the other common early returns in
     // this method.
     ContentChild* contentChild = ContentChild::GetSingleton();

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/ContentDelegateTest.kt

@@ -350,7 +350,6 @@ class ContentDelegateTest : BaseSessionTest() {
     private fun setHangReportTestPrefs(timeout: Int = 20000) {
         sessionRule.setPrefsUntilTestEnd(mapOf(
                 "dom.max_script_run_time" to 1,
-                "dom.max_script_run_time_without_important_user_input" to 1,
                 "dom.max_chrome_script_run_time" to 1,
                 "dom.max_ext_content_script_run_time" to 1,
                 "dom.ipc.cpow.timeout" to 100,

modules/libpref/init/StaticPrefList.yaml

@@ -3539,19 +3539,28 @@
   value: @IS_ANDROID@
   mirror: always
 
-# The following four prefs control the maximum script run time before slow
+# The following three prefs control the maximum script run time before slow
 # script warning.
+
+# Controls the time that a content script can run before showing a
+# notification.
 - name: dom.max_script_run_time
   type: int32_t
   value: 10
   mirror: always
 
-- name: dom.max_script_run_time_without_important_user_input
-  type: int32_t
-#ifdef NIGHTLY_BUILD
-  value: 20
+# Controls whether we want to wait for user input before surfacing notifying
+# the parent process about a long-running script.
+- name: dom.max_script_run_time.require_critical_input
+  type: bool
+# On desktop, we don't want to annoy the user with a notification if they're
+# not interacting with the browser. On Android however, we automatically
+# terminate long-running scripts, so we want to make sure we don't get in the
+# way of that by waiting for input.
+#if defined(MOZ_WIDGET_ANDROID)
+  value: false
 #else
-  value: 10
+  value: true
 #endif
   mirror: always