Bug 721413 - [New Tab Page] Load links lazily when opening a new tab; r=mak

browser/base/content/browser.js

@@ -174,9 +174,6 @@ XPCOMUtils.defineLazyGetter(this, "PopupNotifications", function () {
   }
 });
 
-XPCOMUtils.defineLazyModuleGetter(this, "NewTabUtils",
-  "resource:///modules/NewTabUtils.jsm");
-
 XPCOMUtils.defineLazyGetter(this, "InspectorUI", function() {
   let tmp = {};
   Cu.import("resource:///modules/inspector.jsm", tmp);
@@ -1711,7 +1708,6 @@ function delayedStartup(isLoadingBlank, mustLoadSidebar) {
 #endif
 
   gBrowserThumbnails.init();
-  NewTabUtils.init();
   TabView.init();
 
   setUrlAndSearchBarWidthForConditionalForwardButton();

browser/base/content/newtab/page.js

@@ -77,21 +77,21 @@ let gPage = {
 
     this._initialized = true;
 
-    let self = this;
+    gLinks.populateCache(function () {
+      // Check if the grid is modified.
+      this.updateModifiedFlag();
 
-    // Check if the grid is modified.
-    this.updateModifiedFlag();
+      // Initialize and render the grid.
+      gGrid.init(this._gridSelector);
 
-    // Initialize and render the grid.
-    gGrid.init(this._gridSelector);
+      // Initialize the drop target shim.
+      gDropTargetShim.init();
 
-    // Initialize the drop target shim.
-    gDropTargetShim.init();
-
-    // Workaround to prevent a delay on MacOSX due to a slow drop animation.
-    let doc = document.documentElement;
-    doc.addEventListener("dragover", this.onDragOver, false);
-    doc.addEventListener("drop", this.onDrop, false);
+      // Workaround to prevent a delay on MacOSX due to a slow drop animation.
+      let doc = document.documentElement;
+      doc.addEventListener("dragover", this.onDragOver, false);
+      doc.addEventListener("drop", this.onDrop, false);
+    }.bind(this));
   },
 
   /**

browser/base/content/newtab/toolbar.js

@@ -60,7 +60,7 @@ let gToolbar = {
 
         // Without the setTimeout() we have a strange flicker.
         setTimeout(function () gTransformation.fadeNodeIn(node, aCallback));
-      });
+      }, true);
     });
   },
 

browser/base/content/test/newtab/head.js

@@ -126,10 +126,15 @@ function addNewTabPageTab() {
 
     cw = browser.contentWindow;
 
-    if (NewTabUtils.allPages.enabled)
+    if (NewTabUtils.allPages.enabled) {
       cells = cw.gGrid.cells;
 
-    TestRunner.next();
+      // Continue when the link cache has been populated.
+      NewTabUtils.links.populateCache(TestRunner.next);
+    } else {
+      TestRunner.next();
+    }
+
   }, true);
 }
 

browser/modules/NewTabUtils.jsm

@@ -464,24 +464,55 @@ let Links = {
   /**
    * The links cache.
    */
-  _links: [],
+  _links: null,
 
   /**
    * The default provider for links.
    */
   _provider: PlacesProvider,
 
+  /**
+   * List of callbacks waiting for the cache to be populated.
+   */
+  _populateCallbacks: [],
+
   /**
    * Populates the cache with fresh links from the current provider.
    * @param aCallback The callback to call when finished (optional).
+   * @param aForce When true, populates the cache even when it's already filled.
    */
-  populateCache: function Links_populateCache(aCallback) {
-    let self = this;
+  populateCache: function Links_populateCache(aCallback, aForce) {
+    let callbacks = this._populateCallbacks;
 
-    this._provider.getLinks(function (aLinks) {
-      self._links = aLinks;
-      aCallback && aCallback();
-    });
+    // Enqueue the current callback.
+    callbacks.push(aCallback);
+
+    // There was a callback waiting already, thus the cache has not yet been
+    // populated.
+    if (callbacks.length > 1)
+      return;
+
+    function executeCallbacks() {
+      while (callbacks.length) {
+        let callback = callbacks.shift();
+        if (callback) {
+          try {
+            callback();
+          } catch (e) {
+            // We want to proceed even if a callback fails.
+          }
+        }
+      }
+    }
+
+    if (this._links && !aForce) {
+      executeCallbacks();
+    } else {
+      this._provider.getLinks(function (aLinks) {
+        this._links = aLinks;
+        executeCallbacks();
+      }.bind(this));
+    }
   },
 
   /**
@@ -520,20 +551,6 @@ let Links = {
  * Singleton that provides the public API of this JSM.
  */
 let NewTabUtils = {
-  _initialized: false,
-
-  /**
-   * Initializes and prepares the NewTabUtils module.
-   */
-  init: function NewTabUtils_init() {
-    if (!this._initialized) {
-      // Prefetch the links.
-      Links.populateCache();
-
-      this._initialized = true;
-    }
-  },
-
   /**
    * Resets the NewTabUtils module, its links and its storage.
    */