Gallery: Remove redundant prefetching.

 * Currently cache of slide image is managed by GalleryItem. So we don't need to
   prefetch images to update cache last accessed time.
 * We should not start another prefetch request if we have already started
   prefetch for the entry.
 * Remove unused inline function.

BUG=None
TEST=None

Review URL: https://codereview.chromium.org/1053993002

Cr-Commit-Position: refs/heads/master@{#323598}

2 files changed, 1 insertions, 22 deletions

diff --git a/ui/file_manager/gallery/js/image_editor/image_view.js b/ui/file_manager/gallery/js/image_editor/image_view.js
index ea37399..76b837f 100644
--- a/ui/file_manager/gallery/js/image_editor/image_view.js
+++ b/ui/file_manager/gallery/js/image_editor/image_view.js
@@ -498,7 +498,7 @@ ImageView.prototype.load =
  * @param {number=} opt_delay Image load delay in ms.
  */
 ImageView.prototype.prefetch = function(item, opt_delay) {
-  if (item.contentImage)
+  if (item.contentImage || this.prefetchLoader_.isLoading(item.getEntry()))
     return;
   this.prefetchLoader_.load(item, function(canvas) {
     if (canvas.width && canvas.height && !item.contentImage)
diff --git a/ui/file_manager/gallery/js/slide_mode.js b/ui/file_manager/gallery/js/slide_mode.js
index 5095dfd..5451ebe 100644
--- a/ui/file_manager/gallery/js/slide_mode.js
+++ b/ui/file_manager/gallery/js/slide_mode.js
@@ -515,21 +515,6 @@ SlideMode.prototype.enter = function(
   this.sequenceDirection_ = 0;
   this.sequenceLength_ = 0;
 
-  var loadDone = function(loadType, delay) {
-    this.active_ = true;
-
-    this.selectionModel_.addEventListener('change', this.onSelectionBound_);
-    this.dataModel_.addEventListener('splice', this.onSpliceBound_);
-
-    ImageUtil.setAttribute(this.arrowBox_, 'active', this.getItemCount_() > 1);
-    this.ribbon_.enable();
-
-    // Wait 1000ms after the animation is done, then prefetch the next image.
-    this.requestPrefetch(1, delay + 1000);
-
-    if (loadCallback) loadCallback();
-  }.bind(this);
-
   // The latest |leave| call might have left the image animating. Remove it.
   this.unloadImage_();
 
@@ -775,12 +760,6 @@ SlideMode.prototype.loadSelectedItem_ = function() {
   this.displayedItem_ = this.getSelectedItem();
   var selectedItem = assertInstanceof(this.getSelectedItem(), Gallery.Item);
 
-  if (this.sequenceLength_ <= 1) {
-    // We have just broke the sequence. Touch the current image so that it stays
-    // in the cache longer.
-    this.imageView_.prefetch(selectedItem);
-  }
-
   function shouldPrefetch(loadType, step, sequenceLength) {
     // Never prefetch when selecting out of sequence.
     if (Math.abs(step) != 1)