Bug 1548253 - Port pref cache variables of nsContentUtils to StaticPrefs - dom.script_loader.bytecode_cache.enabled, r=Ehsan

Differential Revision: https://phabricator.services.mozilla.com/D29523

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

dom/base/nsContentUtils.cpp

@@ -314,7 +314,6 @@ bool nsContentUtils::sInitialized = false;
 bool nsContentUtils::sBypassCSSOMOriginCheck = false;
 #endif
 
-bool nsContentUtils::sIsBytecodeCacheEnabled = false;
 int32_t nsContentUtils::sBytecodeCacheStrategy = 0;
 nsCString* nsContentUtils::sJSBytecodeMimeType = nullptr;
 
@@ -612,10 +611,6 @@ nsresult nsContentUtils::Init() {
   sBypassCSSOMOriginCheck = getenv("MOZ_BYPASS_CSSOM_ORIGIN_CHECK");
 #endif
 
-  Preferences::AddBoolVarCache(&sIsBytecodeCacheEnabled,
-                               "dom.script_loader.bytecode_cache.enabled",
-                               false);
-
   Preferences::AddBoolVarCache(
       &sAntiTrackingControlCenterUIEnabled,
       "browser.contentblocking.rejecttrackers.control-center.ui.enabled",

dom/base/nsContentUtils.h

@@ -3188,10 +3188,6 @@ class nsContentUtils {
    */
   static bool GetUserIsInteracting();
 
-  // Check pref "dom.script_loader.bytecode_cache.enabled" to see
-  // if we want to cache JS bytecode on the cache entry.
-  static bool IsBytecodeCacheEnabled() { return sIsBytecodeCacheEnabled; }
-
   // Check pref "dom.script_loader.bytecode_cache.strategy" to see which
   // heuristic strategy should be used to trigger the caching of the bytecode.
   static int32_t BytecodeCacheStrategy() { return sBytecodeCacheStrategy; }
@@ -3407,7 +3403,6 @@ class nsContentUtils {
 #ifndef RELEASE_OR_BETA
   static bool sBypassCSSOMOriginCheck;
 #endif
-  static bool sIsBytecodeCacheEnabled;
   static int32_t sBytecodeCacheStrategy;
   static bool sAntiTrackingControlCenterUIEnabled;
 

dom/script/ScriptLoadHandler.cpp

@@ -14,6 +14,7 @@
 #include "nsMimeTypes.h"
 
 #include "mozilla/Telemetry.h"
+#include "mozilla/StaticPrefs.h"
 
 namespace mozilla {
 namespace dom {
@@ -407,7 +408,7 @@ ScriptLoadHandler::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
   // Everything went well, keep the CacheInfoChannel alive such that we can
   // later save the bytecode on the cache entry.
   if (NS_SUCCEEDED(rv) && mRequest->IsSource() &&
-      nsContentUtils::IsBytecodeCacheEnabled()) {
+      StaticPrefs::dom_script_loader_bytecode_cache_enabled()) {
     mRequest->mCacheInfo = do_QueryInterface(channelRequest);
     LOG(("ScriptLoadRequest (%p): nsICacheInfoChannel = %p", mRequest.get(),
          mRequest->mCacheInfo.get()));

dom/script/ScriptLoader.cpp

@@ -1285,7 +1285,7 @@ nsresult ScriptLoader::StartLoad(ScriptLoadRequest* aRequest) {
   // constant.
   aRequest->mCacheInfo = nullptr;
   nsCOMPtr<nsICacheInfoChannel> cic(do_QueryInterface(channel));
-  if (cic && nsContentUtils::IsBytecodeCacheEnabled() &&
+  if (cic && StaticPrefs::dom_script_loader_bytecode_cache_enabled() &&
       // Bug 1436400: no bytecode cache support for modules yet.
       !aRequest->IsModuleRequest()) {
     if (!aRequest->IsLoadingSource()) {

modules/libpref/init/StaticPrefList.h

@@ -538,6 +538,16 @@ VARCACHE_PREF(
 )
 #endif
 
+// Whether to enable the JavaScript start-up cache. This causes one of the first
+// execution to record the bytecode of the JavaScript function used, and save it
+// in the existing cache entry. On the following loads of the same script, the
+// bytecode would be loaded from the cache instead of being generated once more.
+VARCACHE_PREF(
+  "dom.script_loader.bytecode_cache.enabled",
+   dom_script_loader_bytecode_cache_enabled,
+  bool, true
+)
+
 // IMPORTANT: Keep this in condition in sync with all.js. The value
 // of MOZILLA_OFFICIAL is different between full and artifact builds, so without
 // it being specified there, dump is disabled in artifact builds (see Bug 1490412).

modules/libpref/init/all.js

@@ -232,12 +232,6 @@ pref("dom.inputevent.inputtype.enabled", true);
 // Whether the WebMIDI API is enabled
 pref("dom.webmidi.enabled", false);
 
-// Whether to enable the JavaScript start-up cache. This causes one of the first
-// execution to record the bytecode of the JavaScript function used, and save it
-// in the existing cache entry. On the following loads of the same script, the
-// bytecode would be loaded from the cache instead of being generated once more.
-pref("dom.script_loader.bytecode_cache.enabled", true);
-
 // Ignore the heuristics of the bytecode cache, and always record on the first
 // visit. (used for testing purposes).