support animated GIF

ui/file_manager/gallery/js/image_editor/image_util.js

Index: ui/file_manager/gallery/js/image_editor/image_util.js
diff --git a/ui/file_manager/gallery/js/image_editor/image_util.js b/ui/file_manager/gallery/js/image_editor/image_util.js
index 4d93c7a6a9d44d976f5def126f017db10e6c96a9..3fc7a2915b3b675145245c60ff81d1f91d4dfee3 100644
--- a/ui/file_manager/gallery/js/image_editor/image_util.js
+++ b/ui/file_manager/gallery/js/image_editor/image_util.js
@@ -440,7 +440,6 @@ ImageUtil.ImageLoader = function(document, metadataModel) {
    */
   this.metadataModel_ = metadataModel;
 
-  this.image_ = new Image();
   this.generation_ = 0;
 
   /**
@@ -480,7 +479,8 @@ ImageUtil.ImageLoader.prototype.load = function(item, callback, opt_delay) {
   this.entry_ = entry;
   this.callback_ = callback;
 
-  var targetImage = this.image_;
+  var targetImage = assertInstanceof(this.document_.createElement('img'),
+      HTMLImageElement);
   // The transform fetcher is not cancellable so we need a generation counter.
   var generation = ++this.generation_;
 
@@ -491,7 +491,7 @@ ImageUtil.ImageLoader.prototype.load = function(item, callback, opt_delay) {
   var onTransform = function(image, opt_transform) {
     if (generation === this.generation_) {
       this.convertImage_(
-          image, opt_transform || { scaleX: 1, scaleY: 1, rotate90: 0});
+          image, opt_transform);

[yawano, 2016/01/20 06:41:33]

nit: this line also fits in one line.

[ryoh, 2016/01/21 03:19:55]

Done.

     }
   };
   onTransform = onTransform.bind(this);
@@ -540,9 +540,6 @@ ImageUtil.ImageLoader.prototype.load = function(item, callback, opt_delay) {
     if (generation !== this.generation_)
       return;
 
-    // Target current image.
-    targetImage = this.image_;
-
     // Obtain target URL.
     if (FileType.isRaw(entry)) {
       var timestamp =
@@ -610,14 +607,6 @@ ImageUtil.ImageLoader.prototype.cancel = function() {
     clearTimeout(this.timeout_);
     this.timeout_ = 0;
   }
-  if (this.image_) {
-    this.image_.onload = function() {};
-    this.image_.onerror = function() {};
-    // Force to free internal image by assigning empty image.
-    this.image_.src = 'data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAA' +
-        'AAABAAEAAAICTAEAOw==';
-    this.image_ = document.createElement('img');
-  }
   this.generation_++;  // Silence the transform fetcher if it is in progress.
 };
 
@@ -627,6 +616,18 @@ ImageUtil.ImageLoader.prototype.cancel = function() {
  * @private
  */
 ImageUtil.ImageLoader.prototype.convertImage_ = function(image, transform) {
+  if (!transform ||
+        (transform.rotate90 === 0 &&
+         transform.scaleX === 1 &&
+         transform.scaleY === 1)) {
+    try {

[hirono, 2016/01/20 06:07:09]

Why is this try closure needed?

[ryoh, 2016/01/21 03:19:55]

It's copied from here:
https://code.google.com/p/chromium/codesearch#chromium/src/ui/file_manager/ga...

I think this try block is also not required.
I will remove both of them.

+      setTimeout(this.callback_, 0, image);
+    } catch (e) {
+      console.error(e);
+    }
+    this.callback_ = null;
+    return;
+  }
   var canvas = this.document_.createElement('canvas');
 
   if (transform.rotate90 & 1) {  // Rotated +/-90deg, swap the dimensions.