Move WEBPImageDecoder to SkCodec

Move WEBPImageDecoder to SkCodec

SkCodec is gaining advantages over Blink's image decoders.
scroggo@ has a nice summary:

- Skia already has some features that Chromium is interested in:
  - decoding scaled versions of images
  - decoding subsets (i.e. issue 468914)
  - SIMD optimizations for writing pixels
- In general, sharing code means that new features/bug fixes in Android
  benefit Chromium and vice versa
- Skia's API is designed to allow the client to handle caching, so that
  the client that knows the bigger picture can make caching decisions in
  a more informed way than ImageDecoder can.

BUG=715821

[cblume, 2017-04-26 23:24:01]

Description was changed from

==========
Move webp image decoder to SkCodec

SkCodec is gaining advantages over Blink's image decoders.
scroggo@ has a nice summary:

- Skia already has some features that Chromium is interested in:
  - decoding scaled versions of images
  - decoding subsets (i.e. issue 468914)
  - SIMD optimizations for writing pixels
- In general, sharing code means that new features/bug fixes in Android
  benefit Chromium and vice versa
- Skia's API is designed to allow the client to handle caching, so that
  the client that knows the bigger picture can make caching decisions in
  a more informed way than ImageDecoder can.

BUG=663569
==========

to

==========
Move WEBPImageDecoder to SkCodec

SkCodec is gaining advantages over Blink's image decoders.
scroggo@ has a nice summary:

- Skia already has some features that Chromium is interested in:
  - decoding scaled versions of images
  - decoding subsets (i.e. issue 468914)
  - SIMD optimizations for writing pixels
- In general, sharing code means that new features/bug fixes in Android
  benefit Chromium and vice versa
- Skia's API is designed to allow the client to handle caching, so that
  the client that knows the bigger picture can make caching decisions in
  a more informed way than ImageDecoder can.

BUG=715821
==========

[cblume, 2017-06-01 23:28:03]

The CQ bit was checked by cblume@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-06-01 23:28:47]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-06-01 23:56:37]

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

[commit-bot: I haz the power, 2017-06-01 23:56:38]

Dry run: Try jobs failed on following builders:
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[cblume, 2017-06-02 09:19:15]

The CQ bit was checked by cblume@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-06-02 09:19:21]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-06-02 10:54:11]

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

[commit-bot: I haz the power, 2017-06-02 10:54:12]

Dry run: Try jobs failed on following builders:
  linux_chromium_chromeos_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[cblume, 2017-08-08 08:31:30]

cblume@chromium.org changed reviewers:
+ scroggo@chromium.org

[cblume, 2017-08-08 08:33:30]

This patch relies on 2 pending Skia patches:
* Allow SkStream-derived classes to move. --
https://skia-review.googlesource.com/c/24580
* Expose blend source for WebP users of SkCodec --
https://bugs.chromium.org/p/skia/issues/detail?id=6928