Bug 1570082 - Convert content.notify.backoffcount to static pref. r=njn

Converts content.notify.backoffcount varcache pref to static pref.

Differential Revision: https://phabricator.services.mozilla.com/D40133

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

dom/base/nsContentSink.cpp

@@ -135,7 +135,6 @@ nsContentSink::~nsContentSink() {
   }
 }
 
-int32_t nsContentSink::sBackoffCount;
 int32_t nsContentSink::sNotificationInterval;
 int32_t nsContentSink::sInteractiveDeflectCount;
 int32_t nsContentSink::sPerfDeflectCount;
@@ -148,9 +147,6 @@ int32_t nsContentSink::sInitialPerfTime;
 int32_t nsContentSink::sEnablePerfMode;
 
 void nsContentSink::InitializeStatics() {
-  // -1 means never.
-  Preferences::AddIntVarCache(&sBackoffCount, "content.notify.backoffcount",
-                              -1);
   // The gNotificationInterval has a dramatic effect on how long it
   // takes to initially display content for slow connections.
   // The current value provides good
@@ -210,7 +206,7 @@ nsresult nsContentSink::Init(Document* aDoc, nsIURI* aURI,
 
   mNodeInfoManager = aDoc->NodeInfoManager();
 
-  mBackoffCount = sBackoffCount;
+  mBackoffCount = StaticPrefs::content_notify_backoffcount();
 
   if (sEnablePerfMode != 0) {
     mDynamicLowerValue = sEnablePerfMode == 1;

dom/base/nsContentSink.h

@@ -337,8 +337,6 @@ class nsContentSink : public nsICSSLoaderObserver,
   nsRevocableEventPtr<nsRunnableMethod<nsContentSink, void, false> >
       mProcessLinkHeaderEvent;
 
-  // Back off timer notification after count.
-  static int32_t sBackoffCount;
   // Notification interval in microseconds
   static int32_t sNotificationInterval;
   // How many times to deflect in interactive/perf modes

modules/libpref/init/StaticPrefList.yaml

@@ -978,6 +978,13 @@
 # Prefs starting with "content."
 #---------------------------------------------------------------------------
 
+# Back off timer notification after count.
+# -1 means never.
+- name: content.notify.backoffcount
+  type: int32_t
+  value: -1
+  mirror: always
+
 # Do we notify based on time?
 - name: content.notify.ontimer
   type: bool