[filebrowser] Improve scrolling by converting some async calls to sync.

chrome/browser/resources/file_manager/js/file_manager.js

Index: chrome/browser/resources/file_manager/js/file_manager.js
===================================================================
--- chrome/browser/resources/file_manager/js/file_manager.js	(revision 108087)
+++ chrome/browser/resources/file_manager/js/file_manager.js	(working copy)
@@ -425,7 +425,7 @@
    * @param {function(Entry)} successCallback The function to invoke once the
    *     file size is known.
    */
-  function cacheEntrySize(entry, successCallback, opt_errorCallback) {
+  function cacheEntrySize(entry, successCallback, opt_errorCallback, opt_sync) {

[Vladislav Kaznacheev, 2011/11/08 09:33:31]

Please update JSDoc

[dgozman, 2011/11/14 09:59:26]

Done.

     if (entry.isDirectory) {
       // No size for a directory, -1 ensures it's sorted before 0 length files.
       entry.cachedSize_ = -1;
@@ -435,7 +435,12 @@
       if (successCallback) {
         // Callback via a setTimeout so the sync/async semantics don't change

[Vladislav Kaznacheev, 2011/11/08 09:33:31]

Comment is now obsolete here and below. Here is an idea: why don't we extract an
utility function invokeCallback(callback, opt_sync) and use it in the three
places? And comment why we need it?

[dgozman, 2011/11/14 09:59:26]

Done.

         // based on whether or not the value is cached.
-        setTimeout(function() { successCallback(entry) }, 0);
+        if (opt_sync) {
+          // If opt_sync, we are safe with synchronous call (which is faster).
+          successCallback(entry);
+        } else {
+          setTimeout(function() { successCallback(entry) }, 0);
+        }
       }
       return;
     }
@@ -458,12 +463,17 @@
    * @param {function(Entry)} successCallback The function to invoke once the
    *     mtime is known.
    */
-  function cacheEntryDate(entry, successCallback, opt_errorCallback) {
+  function cacheEntryDate(entry, successCallback, opt_errorCallback, opt_sync) {

[Vladislav Kaznacheev, 2011/11/08 09:33:32]

Please update JSDoc

[dgozman, 2011/11/14 09:59:26]

Done.

     if ('cachedMtime_' in entry) {
       if (successCallback) {
-        // Callback via a setTimeout so the sync/async semantics don't change
-        // based on whether or not the value is cached.
-        setTimeout(function() { successCallback(entry) }, 0);
+        if (opt_sync) {
+          // We are safe to make synchronous callback.
+          successCallback(entry);
+        } else {
+          // Callback via a setTimeout so the sync/async semantics don't change
+          // based on whether or not the value is cached.
+          setTimeout(function() { successCallback(entry) }, 0);
+        }
       }
       return;
     }
@@ -762,12 +772,19 @@
    * @param {Entry} entry An HTML5 Entry object.
    * @param {function(Entry)} successCallback The function to invoke once the
    *     file size is known.
+   * @param {boolean=} opt_sync If true, we are safe to do synchronous callback.
    */
-  FileManager.prototype.cacheEntryFileType = function(entry, successCallback) {
+  FileManager.prototype.cacheEntryFileType = function(
+      entry, successCallback, opt_sync) {
     this.getFileType(entry);
 
-    if (successCallback)
-      setTimeout(function() { successCallback(entry) }, 0);
+    if (successCallback) {
+      if (opt_sync) {
+        successCallback(entry);
+      } else {
+        setTimeout(function() { successCallback(entry) }, 0);
+      }
+    }
   };
 
   /**
@@ -1552,7 +1569,7 @@
 
     var icon = this.document_.createElement('div');
     icon.className = 'detail-icon';
-    this.cacheEntryIconType(entry);
+    this.getIconType(entry);
     icon.setAttribute('iconType', entry.cachedIconType_);
     div.appendChild(icon);
 
@@ -1613,7 +1630,7 @@
       } else {
         div.textContent = util.bytesToSi(entry.cachedSize_);
       }
-    });
+    }, null, true);
 
     return div;
   };
@@ -1629,7 +1646,6 @@
     var div = this.document_.createElement('div');
     div.className = 'detail-type';
 
-    div.textContent = '...';
     this.cacheEntryFileType(entry, function(entry) {
       var info = entry.cachedFileType_;
       if (info.name) {
@@ -1639,7 +1655,7 @@
           div.textContent = str(info.name);
       } else
         div.textContent = '';
-    });
+    }, true);
 
     return div;
   };
@@ -1667,7 +1683,7 @@
       } else {
         div.textContent = self.shortDateFormatter_.format(entry.cachedMtime_);
       }
-    });
+    }, null, true);
 
     return div;
   };