Bug 1376602 - Part 1: Import sources for WebCompat Go Faster 1.2. r=Felipe

MozReview-Commit-ID: cLuF81S7H4

--HG--
extra : rebase_source : 3a92adf155da360e42c8fddc59d131907124b7df

browser/extensions/webcompat/bootstrap.js

@@ -2,12 +2,15 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
-Components.utils.import("resource://gre/modules/Services.jsm");
+const {utils: Cu} = Components;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
 
 const PREF_BRANCH = "extensions.webcompat.";
 const PREF_DEFAULTS = {perform_ua_overrides: true};
 
+const UA_OVERRIDES_INIT_TOPIC = "useragentoverrides-initialized";
 const UA_ENABLE_PREF_NAME = "extensions.webcompat.perform_ua_overrides";
 
 XPCOMUtils.defineLazyModuleGetter(this, "UAOverrider", "chrome://webcompat/content/lib/ua_overrider.jsm");
@@ -21,7 +24,6 @@ function UAEnablePrefObserver() {
     overrider = new UAOverrider(UAOverrides);
     overrider.init();
   } else if (!isEnabled && overrider) {
-    overrider.uninit();
     overrider = null;
   }
 }
@@ -60,14 +62,24 @@ this.startup = function({webExtension}) {
   Services.prefs.clearUserPref(UA_ENABLE_PREF_NAME);
   Services.prefs.addObserver(UA_ENABLE_PREF_NAME, UAEnablePrefObserver);
 
-  overrider = new UAOverrider(UAOverrides);
-  overrider.init();
+  // Listen to the useragentoverrides-initialized notification we get and
+  // initialize our overrider there. This is done to avoid slowing down the
+  // apparent startup proces, since we avoid loading anything before the first
+  // window is visible to the user. See bug 1371442 for details.
+  let startupWatcher = {
+    observe(aSubject, aTopic, aData) {
+      if (aTopic !== UA_OVERRIDES_INIT_TOPIC) {
+        return;
+      }
+
+      Services.obs.removeObserver(this, UA_OVERRIDES_INIT_TOPIC);
+      overrider = new UAOverrider(UAOverrides);
+      overrider.init();
+    }
+  };
+  Services.obs.addObserver(startupWatcher, UA_OVERRIDES_INIT_TOPIC);
 };
 
 this.shutdown = function() {
   Services.prefs.removeObserver(UA_ENABLE_PREF_NAME, UAEnablePrefObserver);
-
-  if (overrider) {
-    overrider.uninit();
-  }
 };

browser/extensions/webcompat/content/lib/ua_overrider.jsm

@@ -7,10 +7,8 @@ const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Console.jsm");
 
-const DefaultUA = Cc["@mozilla.org/network/protocol;1?name=http"].getService(Ci.nsIHttpProtocolHandler).userAgent;
-const NS_HTTP_ON_USERAGENT_REQUEST_TOPIC = "http-on-useragent-request";
-
 XPCOMUtils.defineLazyModuleGetter(this, "Services", "resource://gre/modules/Services.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "UserAgentOverrides", "resource://gre/modules/UserAgentOverrides.jsm");
 XPCOMUtils.defineLazyServiceGetter(this, "eTLDService", "@mozilla.org/network/effective-tld-service;1", "nsIEffectiveTLDService");
 
 class UAOverrider {
@@ -35,24 +33,14 @@ class UAOverrider {
   }
 
   init() {
-    Services.obs.addObserver(this, NS_HTTP_ON_USERAGENT_REQUEST_TOPIC);
+    UserAgentOverrides.addComplexOverride(this.overrideCallback.bind(this));
   }
 
-  uninit() {
-    Services.obs.removeObserver(this, NS_HTTP_ON_USERAGENT_REQUEST_TOPIC);
-  }
-
-  observe(subject, topic) {
-    if (topic !== NS_HTTP_ON_USERAGENT_REQUEST_TOPIC) {
-      return;
-    }
-
-    let channel = subject.QueryInterface(Components.interfaces.nsIHttpChannel);
-    let uaOverride = this.lookupUAOverride(channel.URI);
-
+  overrideCallback(channel, defaultUA) {
+    let uaOverride = this.lookupUAOverride(channel.URI, defaultUA);
     if (uaOverride) {
       console.log("The user agent has been overridden for compatibility reasons.");
-      channel.setRequestHeader("User-Agent", uaOverride, false);
+      return uaOverride;
     }
   }
 
@@ -88,12 +76,12 @@ class UAOverrider {
    * If there are more than one possible overrides, that is if two or more
    * uriMatchers would return true, the first one gets applied.
    */
-  lookupUAOverride(uri) {
+  lookupUAOverride(uri, defaultUA) {
     let baseDomain = this.getBaseDomainFromURI(uri);
     if (baseDomain && this._overrides[baseDomain]) {
       for (let uaOverride of this._overrides[baseDomain]) {
         if (uaOverride.uriMatcher(uri.specIgnoringRef)) {
-          return uaOverride.uaTransformer(DefaultUA);
+          return uaOverride.uaTransformer(defaultUA);
         }
       }
     }