Bug 1489072: Fix startup perf regression in pdf.js init. r=bdahl

Differential Revision: https://phabricator.services.mozilla.com/D7649

--HG--
extra : rebase_source : 1a6b6ce514b79f29269812cc33d27be19ada1c02

browser/components/nsBrowserGlue.js

@@ -11,6 +11,8 @@ ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
 ChromeUtils.defineModuleGetter(this, "ActorManagerParent",
                                "resource://gre/modules/ActorManagerParent.jsm");
 
+const PREF_PDFJS_ENABLED_CACHE_STATE = "pdfjs.enabledCache.state";
+
 let ACTORS = {
   AboutReader: {
     child: {
@@ -993,7 +995,13 @@ BrowserGlue.prototype = {
   _beforeUIStartup: function BG__beforeUIStartup() {
     SessionStartup.init();
 
-    PdfJs.earlyInit();
+    if (Services.prefs.prefHasUserValue(PREF_PDFJS_ENABLED_CACHE_STATE)) {
+      Services.ppmm.sharedData.set(
+        "pdfjs.enabled",
+        Services.prefs.getBoolPref(PREF_PDFJS_ENABLED_CACHE_STATE));
+    } else {
+      PdfJs.earlyInit();
+    }
 
     // check if we're in safe mode
     if (Services.appinfo.inSafeMode) {

browser/extensions/pdfjs/content/PdfJs.jsm

@@ -108,6 +108,8 @@ var PdfJs = {
   },
 
   earlyInit() {
+    // Note: Please keep this in sync with the duplicated logic in
+    // nsBrowserGlue.js.
     Services.ppmm.sharedData.set("pdfjs.enabled", this.checkEnabled());
   },