support animated GIF

ui/file_manager/file_manager/background/js/test_util_base.js

Index: ui/file_manager/file_manager/background/js/test_util_base.js
diff --git a/ui/file_manager/file_manager/background/js/test_util_base.js b/ui/file_manager/file_manager/background/js/test_util_base.js
index 772e48d5f0334ad310c095d863cf89e3ec1e5f8e..372f6359bc8ebe359c00bda3666b8bcf828355f8 100644
--- a/ui/file_manager/file_manager/background/js/test_util_base.js
+++ b/ui/file_manager/file_manager/background/js/test_util_base.js
@@ -31,6 +31,7 @@ function extractElementInfo(element, contentWindow, opt_styleNames) {
     styles[styleNames[i]] = computedStyles[styleNames[i]];
   }
   var text = element.textContent;
+  var size = element.getBoundingClientRect();
   return {
     attributes: attributes,
     text: text,
@@ -38,7 +39,11 @@ function extractElementInfo(element, contentWindow, opt_styleNames) {
     styles: styles,
     // The hidden attribute is not in the element.attributes even if
     // element.hasAttribute('hidden') is true.
-    hidden: !!element.hidden
+    hidden: !!element.hidden,
+    width: Number(element.width),

[yawano, 2016/01/22 05:03:12]

Why don't you simply use renderedWidth? I don't think we need to have this width
attribute here.

[ryoh, 2016/01/22 05:20:49]

It's needed to check both "size":
 - "width/height" for testing that images are loaded correctly.
 - "renderedWidth/renderedHeight" for testing that images are scaled correctly.

There are two canvases before, full-res and device-res,
so all we need to check is only width/height for these two canvases.

We have only a full-res image now,
so we have to check these two attributes instead.

[yawano, 2016/01/22 05:52:04]

I get it. Thank you!

nit: many of other elements don't have width/height fields. How about to rename
this to imageWidth and set it only when element is image? Setting undefined will
be okay if element is not image.

[ryoh, 2016/01/22 06:46:03]

Done.

[yawano, 2016/01/22 07:02:49]

nit: 0 will be set even if the element doesn't have width field.

+    height: Number(element.height),
+    renderedWidth: size.width,
+    renderedHeight: size.height
   };
 }