Bug 1569004 - Convert dom.min_timeout_value to StaticPref r=njn

Converts dom.min_timeout_value varcache pref from TimeoutManager::Initialize() to a static pref, and removes its entry and associated constants from TimeoutManager.cpp and all.js

Differential Revision: https://phabricator.services.mozilla.com/D39416

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

dom/base/TimeoutManager.cpp

@@ -8,6 +8,7 @@
 #include "nsGlobalWindow.h"
 #include "mozilla/Logging.h"
 #include "mozilla/PerformanceCounter.h"
+#include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/StaticPrefs_privacy.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/ThrottledEventQueue.h"
@@ -34,11 +35,9 @@ LazyLogModule gTimeoutLog("Timeout");
 static int32_t gRunningTimeoutDepth = 0;
 
 // The default shortest interval/timeout we permit
-#define DEFAULT_MIN_CLAMP_TIMEOUT_VALUE 4                   // 4ms
 #define DEFAULT_MIN_BACKGROUND_TIMEOUT_VALUE 1000           // 1000ms
 #define DEFAULT_MIN_TRACKING_TIMEOUT_VALUE 4                // 4ms
 #define DEFAULT_MIN_TRACKING_BACKGROUND_TIMEOUT_VALUE 1000  // 1000ms
-static int32_t gMinClampTimeoutValue = 0;
 static int32_t gMinBackgroundTimeoutValue = 0;
 static int32_t gMinTrackingTimeoutValue = 0;
 static int32_t gMinTrackingBackgroundTimeoutValue = 0;
@@ -326,8 +325,9 @@ TimeDuration TimeoutManager::CalculateDelay(Timeout* aTimeout) const {
   TimeDuration result = aTimeout->mInterval;
 
   if (aTimeout->mNestingLevel >= DOM_CLAMP_TIMEOUT_NESTING_LEVEL) {
-    result = TimeDuration::Max(
-        result, TimeDuration::FromMilliseconds(gMinClampTimeoutValue));
+    uint32_t minTimeoutValue = StaticPrefs::dom_min_timeout_value();
+    result = TimeDuration::Max(result,
+                               TimeDuration::FromMilliseconds(minTimeoutValue));
   }
 
   return result;
@@ -479,8 +479,6 @@ TimeoutManager::~TimeoutManager() {
 
 /* static */
 void TimeoutManager::Initialize() {
-  Preferences::AddIntVarCache(&gMinClampTimeoutValue, "dom.min_timeout_value",
-                              DEFAULT_MIN_CLAMP_TIMEOUT_VALUE);
   Preferences::AddIntVarCache(&gMinBackgroundTimeoutValue,
                               "dom.min_background_timeout_value",
                               DEFAULT_MIN_BACKGROUND_TIMEOUT_VALUE);

modules/libpref/init/StaticPrefList.yaml

@@ -1423,6 +1423,12 @@
   value: false
   mirror: always
 
+# Timeout clamp in ms for timeouts we clamp.
+- name: dom.min_timeout_value
+  type: int32_t
+  value: 4
+  mirror: always
+
 # Is support for module scripts (<script type="module">) enabled for content?
 - name: dom.moduleScripts.enabled
   type: bool

modules/libpref/init/all.js

@@ -1084,8 +1084,6 @@ pref("dom.storage.client_validation", true);
 
 pref("dom.send_after_paint_to_content", false);
 
-// Timeout clamp in ms for timeouts we clamp
-pref("dom.min_timeout_value", 4);
 // And for background windows
 pref("dom.min_background_timeout_value", 1000);
 // Timeout clamp in ms for tracking timeouts we clamp