From 0f9f0f8a9b8fc1f6c39660c0d90ec96e75daa67b Mon Sep 17 00:00:00 2001
From: Doug Thayer <dougathayer@gmail.com>
Date: Tue, 22 Aug 2017 12:01:55 -0700
Subject: [PATCH] Cache PdfJs's enabled setting for delayed init

See Bug 1389443 for more information. This allows us to register
PdfJs without waiting for file IO in nsHandlerService to finish.
Once that file IO is finished, we can set everything up properly
and double-check the registration.
---
 extensions/firefox/content/PdfJs.jsm | 68 +++++++++++++++++++---------
 1 file changed, 47 insertions(+), 21 deletions(-)

diff --git a/extensions/firefox/content/PdfJs.jsm b/extensions/firefox/content/PdfJs.jsm
index 263186b54..1cd4259b8 100644
--- a/extensions/firefox/content/PdfJs.jsm
+++ b/extensions/firefox/content/PdfJs.jsm
@@ -30,6 +30,10 @@ const PREF_PREVIOUS_ACTION = PREF_PREFIX + ".previousHandler.preferredAction";
 const PREF_PREVIOUS_ASK = PREF_PREFIX +
                           ".previousHandler.alwaysAskBeforeHandling";
 const PREF_DISABLED_PLUGIN_TYPES = "plugin.disable_full_page_plugin_for_types";
+const PREF_ENABLED_CACHE_STATE = PREF_PREFIX + ".enabledCache.state";
+const PREF_ENABLED_CACHE_INITIALIZED = PREF_PREFIX +
+                                       ".enabledCache.initialized";
+const PREF_APP_UPDATE_POSTUPDATE = "app.update.postupdate";
 const TOPIC_PDFJS_HANDLER_CHANGED = "pdfjs:handlerChanged";
 const TOPIC_PLUGINS_LIST_UPDATED = "plugins-list-updated";
 const TOPIC_PLUGIN_INFO_UPDATED = "plugin-info-updated";
@@ -171,7 +175,7 @@ var PdfJs = {
   },
 
   updateRegistration: function updateRegistration() {
-    if (this.enabled) {
+    if (this.checkEnabled()) {
       this.ensureRegistered();
     } else {
       this.ensureUnregistered();
@@ -250,26 +254,7 @@ var PdfJs = {
                                         false);
   },
 
-  // nsIObserver
-  observe: function observe(aSubject, aTopic, aData) {
-    if (Services.appinfo.processType !==
-        Services.appinfo.PROCESS_TYPE_DEFAULT) {
-      throw new Error("Only the parent process should be observing PDF " +
-                      "handler changes.");
-    }
-
-    this.updateRegistration();
-    let jsm = "resource://pdf.js/PdfjsChromeUtils.jsm";
-    let PdfjsChromeUtils = Components.utils.import(jsm, {}).PdfjsChromeUtils;
-    PdfjsChromeUtils.notifyChildOfSettingsChange(this.enabled);
-  },
-
-  /**
-   * pdf.js is only enabled if it is both selected as the pdf viewer and if the
-   * global switch enabling it is true.
-   * @return {boolean} Whether or not it's enabled.
-   */
-  get enabled() {
+  _isEnabled: function _isEnabled() {
     var disabled = getBoolPref(PREF_DISABLED, true);
     if (disabled) {
       return false;
@@ -309,6 +294,47 @@ var PdfJs = {
     return !enabledPluginFound;
   },
 
+  checkEnabled: function checkEnabled() {
+    let isEnabled = this._isEnabled();
+    // This will be updated any time we observe a dependency changing, since
+    // updateRegistration internally calls enabled.
+    Services.prefs.setBoolPref(PREF_ENABLED_CACHE_STATE, isEnabled);
+    return isEnabled;
+  },
+
+  // nsIObserver
+  observe: function observe(aSubject, aTopic, aData) {
+    if (Services.appinfo.processType !==
+        Services.appinfo.PROCESS_TYPE_DEFAULT) {
+      throw new Error("Only the parent process should be observing PDF " +
+                      "handler changes.");
+    }
+
+    this.updateRegistration();
+    let jsm = "resource://pdf.js/PdfjsChromeUtils.jsm";
+    let PdfjsChromeUtils = Components.utils.import(jsm, {}).PdfjsChromeUtils;
+    PdfjsChromeUtils.notifyChildOfSettingsChange(this.enabled);
+  },
+
+  /**
+   * pdf.js is only enabled if it is both selected as the pdf viewer and if the
+   * global switch enabling it is true.
+   * @return {boolean} Whether or not it's enabled.
+   */
+  get enabled() {
+    if (!Services.prefs.getBoolPref(PREF_ENABLED_CACHE_INITIALIZED, false)) {
+      // If we just updated, and the cache hasn't been initialized, then we
+      // can't assume a default state, and need to synchronously initialize
+      // PdfJs
+      if (Services.prefs.prefHasUserValue(PREF_APP_UPDATE_POSTUPDATE)) {
+        this.checkEnabled();
+      }
+
+      Services.prefs.setBoolPref(PREF_ENABLED_CACHE_INITIALIZED, true);
+    }
+    return Services.prefs.getBoolPref(PREF_ENABLED_CACHE_STATE, true);
+  },
+
   ensureRegistered: function ensureRegistered() {
     if (this._registered) {
       return;