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

Converts dom.timeout.enable_budget_timer_throttling from varcache pref to static pref, removes entry from all.js, adds entry to StaticPrefList.yaml. Uses the all.js value and not the value declared in TimeoutManager.cpp. Since this removes the last varcache pref from TimeoutManager::Initialize(), I also removed the Initialize() function and its call in nsGlobalWindowInner.

Differential Revision: https://phabricator.services.mozilla.com/D39455

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

dom/base/TimeoutManager.cpp

@@ -34,9 +34,6 @@ LazyLogModule gTimeoutLog("Timeout");
 
 static int32_t gRunningTimeoutDepth = 0;
 
-#define DEFAULT_ENABLE_BUDGET_TIMEOUT_THROTTLING false
-static bool gEnableBudgetTimeoutThrottling = false;
-
 // static
 const uint32_t TimeoutManager::InvalidFiringId = 0;
 
@@ -447,13 +444,6 @@ TimeoutManager::~TimeoutManager() {
           ("TimeoutManager %p destroyed\n", this));
 }
 
-/* static */
-void TimeoutManager::Initialize() {
-  Preferences::AddBoolVarCache(&gEnableBudgetTimeoutThrottling,
-                               "dom.timeout.enable_budget_timer_throttling",
-                               DEFAULT_ENABLE_BUDGET_TIMEOUT_THROTTLING);
-}
-
 uint32_t TimeoutManager::GetTimeoutId(Timeout::Reason aReason) {
   switch (aReason) {
     case Timeout::Reason::eIdleCallbackTimeout:
@@ -1307,7 +1297,8 @@ void TimeoutManager::StartThrottlingTimeouts() {
   MOZ_DIAGNOSTIC_ASSERT(!mThrottleTimeouts);
   mThrottleTimeouts = true;
   mThrottleTrackingTimeouts = true;
-  mBudgetThrottleTimeouts = gEnableBudgetTimeoutThrottling;
+  mBudgetThrottleTimeouts =
+      StaticPrefs::dom_timeout_enable_budget_timer_throttling();
   mThrottleTimeoutsTimer = nullptr;
 }
 

dom/base/TimeoutManager.h

@@ -80,9 +80,6 @@ class TimeoutManager final {
   // to the background or foreground.
   void UpdateBackgroundState();
 
-  // Initialize TimeoutManager before the first time it is accessed.
-  static void Initialize();
-
   // The document finished loading
   void OnDocumentLoaded();
   void StartThrottlingTimeouts();

dom/base/nsGlobalWindowInner.cpp

@@ -907,16 +907,6 @@ nsGlobalWindowInner::nsGlobalWindowInner(nsGlobalWindowOuter* aOuterWindow)
     }
   }
 
-  // We could have failed the first time through trying
-  // to create the entropy collector, so we should
-  // try to get one until we succeed.
-
-  static bool sFirstTime = true;
-  if (sFirstTime) {
-    sFirstTime = false;
-    TimeoutManager::Initialize();
-  }
-
   if (gDumpFile == nullptr) {
     nsAutoCString fname;
     Preferences::GetCString("browser.dom.window.dump.file", fname);

modules/libpref/init/StaticPrefList.yaml

@@ -1851,6 +1851,12 @@
   value: 15000
   mirror: always
 
+# Turn on budget throttling by default.
+- name: dom.timeout.enable_budget_timer_throttling
+  type: bool
+  value: true
+  mirror: always
+
 # Should we defer timeouts and intervals while loading a page.  Released
 # on Idle or when the page is loaded.
 - name: dom.timeout.defer_during_load

modules/libpref/init/all.js

@@ -1083,9 +1083,6 @@ pref("dom.storage.client_validation", true);
 
 pref("dom.send_after_paint_to_content", false);
 
-// Turn on budget throttling by default
-pref("dom.timeout.enable_budget_timer_throttling", true);
-
 // Don't use new input types
 pref("dom.experimental_forms", false);