Properly set alpha type in webp decode.

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

[hal.canary, 2014-04-03 19:28:18]

On 2014/04/03 17:59:08, scroggo wrote:

As I said in person, it looks good, but let's add a test that verifies that the
bitmaps contain the correct pixels to correspond to their declared alphatype.

[scroggo, 2014-04-03 20:22:09]

On 2014/04/03 19:28:18, Hal Canary wrote:
> On 2014/04/03 17:59:08, scroggo wrote:
> 
> As I said in person, it looks good, but let's add a test that verifies that
the
> bitmaps contain the correct pixels to correspond to their declared alphatype.

Done. PTAL.

[hal.canary, 2014-04-03 20:29:53]

https://codereview.chromium.org/223893002/diff/80001/tests/ImageDecodingTest.cpp
File tests/ImageDecodingTest.cpp (right):

https://codereview.chromium.org/223893002/diff/80001/tests/ImageDecodingTest....
tests/ImageDecodingTest.cpp:266: SkFILEStream stream(fullName.c_str());
skiatest::Test::GetResourcePath() could return a path that isn't the correct
path.  we should print an error and bail out here:

    if (!stream.isValid()) {
        SkDebugf("file %s missing from resource directoy %s\n"
                 basename.c_str(), resourcePath.c_str());
        continue;
    }

[hal.canary, 2014-04-03 20:32:09]

On 2014/04/03 20:29:53, Hal Canary wrote:
> skiatest::Test::GetResourcePath() could return a path that isn't the correct
> path.  ...


Otherwise, LGTM

[scroggo, 2014-04-03 20:34:56]

https://codereview.chromium.org/223893002/diff/80001/tests/ImageDecodingTest.cpp
File tests/ImageDecodingTest.cpp (right):

https://codereview.chromium.org/223893002/diff/80001/tests/ImageDecodingTest....
tests/ImageDecodingTest.cpp:266: SkFILEStream stream(fullName.c_str());
On 2014/04/03 20:29:53, Hal Canary wrote:
> skiatest::Test::GetResourcePath() could return a path that isn't the correct
> path.  we should print an error and bail out here:
> 
>     if (!stream.isValid()) {
>         SkDebugf("file %s missing from resource directoy %s\n"
>                  basename.c_str(), resourcePath.c_str());
>         continue;
>     }

Done.

[scroggo, 2014-04-03 20:35:02]

The CQ bit was checked by scroggo@google.com

[commit-bot: I haz the power, 2014-04-03 20:35:05]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/scroggo@google.com/223893002/100001

[commit-bot: I haz the power, 2014-04-03 20:40:27]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-04-03 20:40:27]

Retried try job too often on Build-Mac10.8-Clang-x86-Release-Trybot for step(s)
BuildBench, BuildEverything, BuildGm, BuildSkiaLib, BuildTests, BuildTools
http://skia-tree-status.appspot.com/redirect/compile-buildbots/buildstatus?bu...

[scroggo, 2014-04-03 20:43:58]

The CQ bit was checked by scroggo@google.com

[commit-bot: I haz the power, 2014-04-03 20:44:06]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/scroggo@google.com/223893002/120001

[commit-bot: I haz the power, 2014-04-03 20:49:23]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-04-03 20:49:25]

Retried try job too often on Build-Ubuntu12-GCC-x86_64-Release-Trybot for
step(s) BuildBench, BuildEverything, BuildGm, BuildSkiaLib, BuildTests,
BuildTools
http://skia-tree-status.appspot.com/redirect/compile-buildbots/buildstatus?bu...

[scroggo, 2014-04-03 20:55:19]

The CQ bit was checked by scroggo@google.com

[commit-bot: I haz the power, 2014-04-03 20:55:22]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/scroggo@google.com/223893002/120001

[commit-bot: I haz the power, 2014-04-03 20:56:05]

Change committed as 14054

[scroggo, 2014-04-03 21:46:52]

A revert of this CL has been created in
https://codereview.chromium.org/223903008/ by scroggo@google.com.

The reason for reverting is: Breaks ImageDecoding tests on several platforms..

[scroggo, 2014-04-24 18:48:42]

On 2014/04/03 21:46:52, scroggo wrote:
> A revert of this CL has been created in
> https://codereview.chromium.org/223903008/ by mailto:scroggo@google.com.
> 
> The reason for reverting is: Breaks ImageDecoding tests on several platforms..

Relanding with https://codereview.chromium.org/252423008/