Implement DownloadImage directly in WebStateImpl

ios/web/web_state/DEPS

Index: ios/web/web_state/DEPS
diff --git a/ios/web/web_state/DEPS b/ios/web/web_state/DEPS
new file mode 100644
index 0000000000000000000000000000000000000000..ee54c22bef5e555a7acf11066e1ea9b81ad3547b
--- /dev/null
+++ b/ios/web/web_state/DEPS
@@ -0,0 +1,4 @@
+include_rules = [
+  "+skia/ext",
+  "+third_party/skia",

[kkhorimoto, 2016/11/28 23:56:50]

I'm pretty sure that we don't want to introduce third_party deps from within
web//.

[Eugene But (OOO till 7-30), 2016/11/30 17:13:49]

+1 Can we use UIKit API for extracting image size? ios/web is a library and we
should be cautious about it's binary size.

[gambard, 2016/12/01 15:14:21]

As explain in another CL: UIImage makes some assumptions about the format/scale
of the image. For example if you download a file favicon.ico containing multiple
images, a UIImage representation will keep only one of them (from my
understanding).

[gambard, 2016/12/01 15:14:21]

Actually, the ImageFetchedCallback type use a SkBitmap as a parameter type, so I
don't see how I can be able to do it without a skia include.

+]