Revert of Properly set alpha type in webp decode. (https://codereview.chromium.org/223893002/)

Reason for revert:
Breaks ImageDecoding tests on several platforms.

Original issue's description:
> Properly set alpha type in webp decode.
>
> Also use the newer setConfig function.
>
> Add a test to confirm that we set the alpha type properly.
>
> Add some images with alpha for testing. (These images are also beneficial for the compare_unpremul test, which was previously not meaningful on 100% opaque images.)
>
> All of the added images are in the public domain. They were taken from https://developers.google.com/speed/webp/gallery2:
>
> yellow_rose:
> "Free Stock Photo in High Resolution - Yellow Rose 3 - Flowers"
> Image Author: Jon Sullivan
> This file is in the public domain.
> http://www.public-domain-photos.com/free-stock-photos-4/flowers/yellow-rose-3.jpg
>
> baby_tux:
> "baby tux for my user page"
> Image Author: Fizyplankton
> This file is in the public domain.
> http://www.minecraftwiki.net/images/8/85/Fizyplankton.png
>
> NOTRY=true
>
> Committed: http://code.google.com/p/skia/source/detail?r=14054

R=halcanary@google.com
TBR=halcanary@google.com
NOTREECHECKS=true
NOTRY=true

Author: scroggo@google.com

Review URL: https://codereview.chromium.org/223903008

git-svn-id: http://skia.googlecode.com/svn/trunk@14055 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/images/SkImageDecoder_libwebp.cpp b/src/images/SkImageDecoder_libwebp.cpp
index 0299025..49d5bd1 100644
--- a/src/images/SkImageDecoder_libwebp.cpp
+++ b/src/images/SkImageDecoder_libwebp.cpp
@@ -298,20 +298,8 @@
         return false;
     }
 
-    SkImageInfo info;
-    info.fWidth = width;
-    info.fHeight = height;
-    info.fColorType = SkBitmapConfigToColorType(config);
-    if (SkToBool(fHasAlpha)) {
-        if (this->getRequireUnpremultipliedColors()) {
-            info.fAlphaType = kUnpremul_SkAlphaType;
-        } else {
-            info.fAlphaType = kPremul_SkAlphaType;
-        }
-    } else {
-        info.fAlphaType = kOpaque_SkAlphaType;
-    }
-    return decodedBitmap->setConfig(info);
+    return decodedBitmap->setConfig(config, width, height, 0,
+                                    fHasAlpha ? kPremul_SkAlphaType : kOpaque_SkAlphaType);
 }
 
 bool SkWEBPImageDecoder::onBuildTileIndex(SkStreamRewindable* stream,