Hide SkEncodedInfo

Bug: skia:7353
Bug: skia:6839

This contains information that is not necessary for clients to know. The
Color enum tells the number of components in the input, but this is only
interesting internally (to the SkSwizzler).

Similarly, the Alpha enum differs from SkAlphaType in that it has
kBinary instead of kPremul. This is useful information only internally
for determining whether the SkColorSpaceXform needs to premultiply.

The bitsPerComponent is potentially useful for a client; Android (in
SkAndroidCodec) uses it to determine the SkColorType. Rather than
exposing bitsPerComponent, use it to make the same decision that Android
would have made - 16 bits per component means to set the info to F16. Add
a test that computeOutputColorType behaves as expected.

Switch conversionSupported to use an SkColorType, which is enough info.

Replace the SkEncodedInfo::Alpha field on SkCodec::FrameInfo with an
SkAlphaType.

SkCodec still needs an SkEncodedInfo, so move its header (which is
already not SK_API) to include/private.

Change-Id: Ie2cf11339bf999ebfd4390c0f448f7edd6feabda
Reviewed-on: https://skia-review.googlesource.com/79260
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Leon Scroggins <scroggo@google.com>
20 files changed