[Gallery] Add reload feature

This patch adds a reload feature, which is that reload the gallery with new entries when a 'onLaunched' event is fired.

BUG=461218
TEST=manually tested

Review URL: https://codereview.chromium.org/959643003

Cr-Commit-Position: refs/heads/master@{#318216}

ui/file_manager/gallery/js/background.js

@@ -23,6 +23,13 @@ var windowCreateOptions = {
 var background = new BackgroundBase();
 
 
+/**
+ * Wrapper of gallery window.
+ * @type {SingletonAppWindowWrapper}
+ */
+var gallery = new SingletonAppWindowWrapper('gallery.html',
+    windowCreateOptions);
+
 // Initializes the strings. This needs for the volume manager.
 var loadTimeDataPromise = new Promise(function(fulfill, reject) {
   chrome.fileManagerPrivate.getStrings(function(stringData) {
@@ -75,17 +82,6 @@ function onLaunched(launchData) {
   });
 }
 
-/**
- * Returns a function to generate an ID for window.
- * @type {function():string} Function which returns an unique id.
- */
-var generateWindowId = (function() {
-  var seq = 0;
-  return function() {
-    return 'GALLERY_' + seq++;
-  };
-})();
-
 /**
  * Opens gallery window.
  * @param {!Array.<string>} urls List of URL to show.
@@ -101,14 +97,8 @@ function openGalleryWindow(urls, reopen) {
     if (urls.length === 0)
       return Promise.reject('No file to open.');
 
-    var windowId = generateWindowId();
-
     // Opens a window.
     return new Promise(function(fulfill, reject) {
-      var gallery = new AppWindowWrapper('gallery.html',
-          windowId,
-          windowCreateOptions);
-
       gallery.launch(
           {urls: urls},
           reopen,

ui/file_manager/gallery/js/gallery.js

@@ -61,6 +61,7 @@ function Gallery(volumeManager) {
   this.selectedEntry_ = null;
   this.metadataCacheObserverId_ = null;
   this.onExternallyUnmountedBound_ = this.onExternallyUnmounted_.bind(this);
+  this.initialized_ = false;
 
   this.dataModel_ = new GalleryDataModel(
       this.context_.metadataCache,
@@ -348,6 +349,11 @@ Gallery.prototype.loadInternal_ = function(entries, selectedEntries) {
       return a.index - b.index;
   });
 
+  if (loadingList.length === 0) {
+    this.dataModel_.splice(0, this.dataModel_.length);
+    return;
+  }
+
   // Load entries.
   // Use the self variable capture-by-closure because it is faster than bind.
   var self = this;
@@ -367,6 +373,14 @@ Gallery.prototype.loadInternal_ = function(entries, selectedEntries) {
       if (chunk.length !== metadataList.length)
         return Promise.reject('Failed to load metadata.');
 
+      // Remove all the previous items if it's the first chunk.
+      // Do it here because prevent a flicker between removing all the items
+      // and adding new ones.
+      if (firstChunk) {
+        self.dataModel_.splice(0, self.dataModel_.length);
+        self.updateThumbnails_();  // Remove the caches.
+      }
+
       // Add items to the model.
       var items = [];
       chunk.forEach(function(chunkItem, index) {
@@ -399,7 +413,7 @@ Gallery.prototype.loadInternal_ = function(entries, selectedEntries) {
         self.onSelection_();
 
       // Init modes after the first chunk is loaded.
-      if (firstChunk) {
+      if (firstChunk && !self.initialized_) {
         // Determine the initial mode.
         var shouldShowMosaic = selectedEntries.length > 1 ||
             (self.context_.pageState &&
@@ -427,6 +441,7 @@ Gallery.prototype.loadInternal_ = function(entries, selectedEntries) {
                 cr.dispatchSimpleEvent(self, 'loaded');
               });
         }
+        self.initialized_ = true;
       }
 
       // Continue to load chunks.
@@ -916,6 +931,17 @@ Gallery.prototype.debugMe = function() {
  */
 var gallery = null;
 
+/**
+ * (Re-)loads entries.
+ */
+function reload() {
+  initializePromise.then(function() {
+    util.URLsToEntries(window.appState.urls, function(entries) {
+      gallery.load(entries);
+    });
+  });
+}
+
 /**
  * Promise to initialize the load time data.
  * @type {!Promise}
@@ -946,27 +972,17 @@ var initializePromise =
     Promise.all([loadTimeDataPromise, volumeManagerPromise]).
     then(function(args) {
       var volumeManager = args[1];
-      var gallery = new Gallery(volumeManager);
-      return gallery;
+      gallery = new Gallery(volumeManager);
     });
 
 // Loads entries.
-initializePromise.then(
-    /**
-     * Loads entries.
-     * @param {!Gallery} gallery The gallery instance.
-     */
-    function(gallery) {
-      util.URLsToEntries(window.appState.urls, function(entries) {
-        gallery.load(entries);
-      });
-    });
+initializePromise.then(reload);
 
 /**
  * Enteres the debug mode.
  */
 window.debugMe = function() {
-  initializePromise.then(function(gallery) {
+  initializePromise.then(function() {
     gallery.debugMe();
   });
 };

ui/file_manager/gallery/js/gallery_scripts.js

@@ -87,6 +87,8 @@
 window.ImageUtil = ImageUtil;
 window.ImageUtil.metrics = metrics;
 window.Gallery = Gallery;
-window.util = util;
+
+window.reload = reload;  // will be called by the background.
+window.gallery = gallery;  // for debug.
 
 })();