Implement refreshing logic in Files app.

ui/file_manager/file_manager/foreground/js/scan_controller.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * Handler for scan related events of DirectoryModel.
  *
  * @param {!DirectoryModel} directoryModel
  * @param {!ListContainer} listContainer
  * @param {!SpinnerController} spinnerController
@@ skipping 115 matching lines @@
   if (this.scanCompletedTimer_) {
     clearTimeout(this.scanCompletedTimer_);
     this.scanCompletedTimer_ = 0;
   }
 
   if (this.scanUpdatedTimer_) {
     clearTimeout(this.scanUpdatedTimer_);
     this.scanUpdatedTimer_ = 0;
   }
 
-  this.spinnerController_.showLater();
+  if (this.directoryModel_.isScanning())
+    this.spinnerController_.showLater();
 };
 
 /**
  * @private
  */
 ScanController.prototype.onScanCompleted_ = function() {
   if (!this.scanInProgress_) {
     console.error('Scan-completed event recieved. But scan is not started.');
     return;
   }
 
   if (this.commandHandler_)
     this.commandHandler_.updateAvailability();
-  this.spinnerController_.hide();
+  this.hideSpinner_();
 
   if (this.scanUpdatedTimer_) {
     clearTimeout(this.scanUpdatedTimer_);
     this.scanUpdatedTimer_ = 0;
   }
 
   // To avoid flickering postpone updating the ui by a small amount of time.
   // There is a high chance, that metadata will be received within 50 ms.
   this.scanCompletedTimer_ = setTimeout(function() {
     // Check if batch updates are already finished by onScanUpdated_().
@@ skipping 18 matching lines @@
 
   if (this.scanUpdatedTimer_ || this.scanCompletedTimer_)
     return;
 
   // Show contents incrementally by finishing batch updated, but only after
   // 200ms elapsed, to avoid flickering when it is not necessary.
   this.scanUpdatedTimer_ = setTimeout(function() {
     // We need to hide the spinner only once.
     if (!this.scanUpdatedAtLeastOnceOrCompleted_) {
       this.scanUpdatedAtLeastOnceOrCompleted_ = true;
-      this.spinnerController_.hide();
+      this.hideSpinner_();
     }
 
     // Update the UI.
     if (this.scanInProgress_) {
       this.listContainer_.endBatchUpdates();
       this.listContainer_.startBatchUpdates();
     }
     this.scanUpdatedTimer_ = 0;
   }.bind(this), 200);
 };
 
 /**
  * @private
  */
 ScanController.prototype.onScanCancelled_ = function() {
   if (!this.scanInProgress_) {
     console.error('Scan-cancelled event recieved. But scan is not started.');
     return;
   }
 
   if (this.commandHandler_)
     this.commandHandler_.updateAvailability();
-  this.spinnerController_.hide();
+  this.hideSpinner_();
   if (this.scanCompletedTimer_) {
     clearTimeout(this.scanCompletedTimer_);
     this.scanCompletedTimer_ = 0;
   }
   if (this.scanUpdatedTimer_) {
     clearTimeout(this.scanUpdatedTimer_);
     this.scanUpdatedTimer_ = 0;
   }
   // Finish unfinished batch updates.
   if (!this.scanUpdatedAtLeastOnceOrCompleted_) {
@@ skipping 32 matching lines @@
 /**
  * When a spinner is shown, updates the UI to remove items in the previous
  * directory.
  */
 ScanController.prototype.onSpinnerShown_ = function() {
   if (this.scanInProgress_) {
     this.listContainer_.endBatchUpdates();
     this.listContainer_.startBatchUpdates();
   }
 };
+
+/**
+ * @private
+ */
+ScanController.prototype.hideSpinner_ = function() {

[hirono, 2015/07/06 09:39:27]

Is the method still needed? The hide method no longer hide the blinking spinner.

[mtomasz, 2015/07/07 03:42:11]

It's used if there is no blinking spinner shown. The blinking spinner is used
only for refreshing via the refresh button.

[hirono, 2015/07/07 03:58:22]

I just noticed the method originally came from SpinnerController. But I still
think we can remove the method. If the method is called by onScanCompleted_ or
onScanCancelled_, directoryModel_.isScanning should be false. And if
onScanUpdated is dispatched, it means we got some entries.

[mtomasz, 2015/07/07 04:01:48]

Ah, got it. Yes, I moved the scanning logic from spinner controller to the
scanner controller. As a result we got rid of the DirectoryModel dependency from
the spinner controller.

It was just copy paste of the logic. Let me remove the conditions in a separate
CL, as I have to think carefully of all edge cases.

+  if (this.directoryModel_.isScanning() &&
+      this.directoryModel_.getFileList().length == 0) {
+    return;
+  }
+  this.spinnerController_.hide();
+};