Bug 1569004 - Convert dom.timeout.max_consecutive_callbacks_ms to static pref. r=njn

Converts dom.timeout.max_consecutive_callbacks_ms varcache pref in TimeoutManager.cpp to static pref, removes associated variables and all.js entry, and adds entry to StaticPrefList.yaml.

Differential Revision: https://phabricator.services.mozilla.com/D39425

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

dom/base/TimeoutManager.cpp

@@ -414,11 +414,6 @@ uint32_t TimeoutManager::sNestingLevel = 0;
 
 namespace {
 
-// The maximum number of milliseconds to allow consecutive timer callbacks
-// to run in a single event loop runnable.
-#define DEFAULT_MAX_CONSECUTIVE_CALLBACKS_MILLISECONDS 4
-uint32_t gMaxConsecutiveCallbacksMilliseconds;
-
 // Only propagate the open window click permission if the setTimeout() is equal
 // to or less than this value.
 #define DEFAULT_DISABLE_OPEN_CLICK_DELAY 0
@@ -467,10 +462,6 @@ TimeoutManager::~TimeoutManager() {
 
 /* static */
 void TimeoutManager::Initialize() {
-  Preferences::AddUintVarCache(&gMaxConsecutiveCallbacksMilliseconds,
-                               "dom.timeout.max_consecutive_callbacks_ms",
-                               DEFAULT_MAX_CONSECUTIVE_CALLBACKS_MILLISECONDS);
-
   Preferences::AddIntVarCache(&gDisableOpenClickDelay,
                               "dom.disable_open_click_delay",
                               DEFAULT_DISABLE_OPEN_CLICK_DELAY);
@@ -682,7 +673,7 @@ void TimeoutManager::RunTimeout(const TimeStamp& aNow,
 
   // Limit the overall time spent in RunTimeout() to reduce jank.
   uint32_t totalTimeLimitMS =
-      std::max(1u, gMaxConsecutiveCallbacksMilliseconds);
+      std::max(1u, StaticPrefs::dom_timeout_max_consecutive_callbacks_ms());
   const TimeDuration totalTimeLimit =
       TimeDuration::Min(TimeDuration::FromMilliseconds(totalTimeLimitMS),
                         TimeDuration::Max(TimeDuration(), mExecutionBudget));

modules/libpref/init/StaticPrefList.yaml

@@ -1819,6 +1819,13 @@
   value: true
   mirror: always
 
+# Maximum amount of time in milliseconds consecutive setTimeout()/setInterval()
+# callback are allowed to run before yielding the event loop.
+- name: dom.timeout.max_consecutive_callbacks_ms
+  type: uint32_t
+  value: 4
+  mirror: always
+
 # Maximum deferral time for setTimeout/Interval in milliseconds
 - name: dom.timeout.max_idle_defer_ms
   type: uint32_t

modules/libpref/init/all.js

@@ -5451,10 +5451,6 @@ pref("browser.sanitizer.loglevel", "Warn");
 // To disable blocking of auth prompts, set the limit to -1.
 pref("prompts.authentication_dialog_abuse_limit", 2);
 
-// Maximum amount of time in milliseconds consecutive setTimeout()/setInterval()
-// callback are allowed to run before yielding the event loop.
-pref("dom.timeout.max_consecutive_callbacks_ms", 4);
-
 // Payment Request API preferences
 pref("dom.payments.loglevel", "Warn");
 pref("dom.payments.defaults.saveCreditCard", false);