Quick View: avoid to lose focus when metadata button is clicked.

ui/file_manager/file_manager/foreground/elements/files_quick_view.js

 // Copyright 2016 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.
 
 var FilesQuickView = Polymer({
   is: 'files-quick-view',
 
   properties: {
     // File media type, e.g. image, video.
     type: String,
@@ skipping 129 matching lines @@
   /**
    * @param {string} type
    * @return {boolean}
    *
    * @private
    */
   isUnsupported_: function(type) {
     return !this.isImage_(type) && !this.isVideo_(type) && !this.isAudio_(type);
   },
 
+  ready: function() {
+    this.$['metadata-button'].addEventListener('click', function(e) {

[fukino, 2016/09/01 09:00:04]

I think adding "on-tap=" attribute for the metadata-button would be simpler.

[oka, 2016/09/01 09:35:47]

Done.

+      // Set focus back to innerContent panel if button is clicked by
+      // mouse or tap so that pressing space key after that closes Quick View.
+      if (e.screenX > 0 || e.screenY > 0) { // clicked by mouse or tap.

[fukino, 2016/09/01 09:00:04]

Can't we always focus the content panel on clicks? Is there a problem?

[oka, 2016/09/01 09:35:47]

Done.
I thought focus should be stick to the button if button is pressed by keyboard,
but moving focus to the main panel is consistent behaviour with the Files App's
button to toggle list view and thumbnail view.

+        e.stopPropagation();
+        e.preventDefault();
+        this.$.innerContentPanel.focus();
+      }
+    }.bind(this));
+  },
+
 });