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

Converts content.notify.interval varcache pref to a static pref. Rewords the description, which referenced 'gNotificationInterval' which no longer existed.

Differential Revision: https://phabricator.services.mozilla.com/D40134

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

dom/base/nsContentSink.cpp

@@ -135,7 +135,6 @@ nsContentSink::~nsContentSink() {
   }
 }
 
-int32_t nsContentSink::sNotificationInterval;
 int32_t nsContentSink::sInteractiveDeflectCount;
 int32_t nsContentSink::sPerfDeflectCount;
 int32_t nsContentSink::sPendingEventMode;
@@ -147,15 +146,6 @@ int32_t nsContentSink::sInitialPerfTime;
 int32_t nsContentSink::sEnablePerfMode;
 
 void nsContentSink::InitializeStatics() {
-  // The gNotificationInterval has a dramatic effect on how long it
-  // takes to initially display content for slow connections.
-  // The current value provides good
-  // incremental display of content without causing an increase
-  // in page load time. If this value is set below 1/10 of second
-  // it starts to impact page load performance.
-  // see bugzilla bug 72138 for more info.
-  Preferences::AddIntVarCache(&sNotificationInterval, "content.notify.interval",
-                              120000);
   Preferences::AddIntVarCache(&sInteractiveDeflectCount,
                               "content.sink.interactive_deflect_count", 0);
   Preferences::AddIntVarCache(&sPerfDeflectCount,

dom/base/nsContentSink.h

@@ -257,7 +257,7 @@ class nsContentSink : public nsICSSLoaderObserver,
       return 1000;
     }
 
-    return sNotificationInterval;
+    return mozilla::StaticPrefs::content_notify_interval();
   }
 
   virtual nsresult FlushTags() = 0;
@@ -337,8 +337,6 @@ class nsContentSink : public nsICSSLoaderObserver,
   nsRevocableEventPtr<nsRunnableMethod<nsContentSink, void, false> >
       mProcessLinkHeaderEvent;
 
-  // Notification interval in microseconds
-  static int32_t sNotificationInterval;
   // How many times to deflect in interactive/perf modes
   static int32_t sInteractiveDeflectCount;
   static int32_t sPerfDeflectCount;

modules/libpref/init/StaticPrefList.yaml

@@ -985,6 +985,18 @@
   value: -1
   mirror: always
 
+# Notification interval in microseconds.
+# The notification interval has a dramatic effect on how long it takes to
+# initially display content for slow connections. The current value
+# provides good incremental display of content without causing an increase
+# in page load time. If this value is set below 1/10 of a second it starts
+# to impact page load performance.
+# See bugzilla bug 72138 for more info.
+- name: content.notify.interval
+  type: int32_t
+  value: 120000
+  mirror: always
+
 # Do we notify based on time?
 - name: content.notify.ontimer
   type: bool