Revert of Checking for valid colorType, alphaType, colorSpace in SkCodec (patchset #2 id:100001 of https://codereview.chromium.org/2319293003/ )

Reason for revert:
Broken perf bots

Original issue's description:
> Checking for valid colorType, alphaType, colorSpace in SkCodec
>
> * Refactor to share code between SkPngCodec and SkWebpCodec
> * Didn't end up sharing with SkJpegCodec but did refactor
>   that code a bit
> * Disallow conversions to F16 with non-linear color spaces
> * Fail to decode if we fail to create a SkColorSpaceXform
>   (should be an assert soon).  We used to fallback on a
>   legacy decode if we failed to create the transform.
> * A bunch of name changes
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2319293003
>
> Committed: https://skia.googlesource.com/skia/+/7a9900d6d34e437bb24beb5524a1f6488ae138c9

TBR=scroggo@google.com,brianosman@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review-Url: https://codereview.chromium.org/2328663002

1 files changed, 2 insertions, 40 deletions

diff --git a/src/codec/SkCodecPriv.h b/src/codec/SkCodecPriv.h
index 4285786304..9a8a43e835 100644
--- a/src/codec/SkCodecPriv.h
+++ b/src/codec/SkCodecPriv.h
@@ -107,18 +107,14 @@ static inline bool valid_alpha(SkAlphaType dstAlpha, SkAlphaType srcAlpha) {
 }
 
 /*
- * Original version of conversion_possible that does not account for color spaces.
- * Used by codecs that have not been updated to support color spaces.
- *
  * Most of our codecs support the same conversions:
  * - opaque to any alpha type
  * - 565 only if opaque
  * - premul to unpremul and vice versa
- * - always support RGBA, BGRA
+ * - always support N32
  * - otherwise match the src color type
  */
-static inline bool conversion_possible_ignore_color_space(const SkImageInfo& dst,
-                                                          const SkImageInfo& src) {
+static inline bool conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
     // Ensure the alpha type is valid
     if (!valid_alpha(dst.alphaType(), src.alphaType())) {
         return false;
@@ -339,38 +335,4 @@ static inline SkAlphaType select_alpha_xform(SkAlphaType dstAlphaType, SkAlphaTy
     return (kOpaque_SkAlphaType == srcAlphaType) ? kOpaque_SkAlphaType : dstAlphaType;
 }
 
-/*
- * Alpha Type Conversions
- * - kOpaque to kOpaque, kUnpremul, kPremul is valid
- * - kUnpremul to kUnpremul, kPremul is valid
- *
- * Color Type Conversions
- * - Always support kRGBA_8888, kBGRA_8888
- * - Support kRGBA_F16 when there is a linear dst color space
- * - Support kIndex8 if it matches the src
- * - Support k565, kGray8 if kOpaque and color correction is not required
- */
-static inline bool conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
-    // Ensure the alpha type is valid.
-    if (!valid_alpha(dst.alphaType(), src.alphaType())) {
-        return false;
-    }
-
-    // Check for supported color types.
-    switch (dst.colorType()) {
-        case kRGBA_8888_SkColorType:
-        case kBGRA_8888_SkColorType:
-            return true;
-        case kRGBA_F16_SkColorType:
-            return dst.colorSpace() && dst.colorSpace()->gammaIsLinear();
-        case kIndex_8_SkColorType:
-            return kIndex_8_SkColorType == src.colorType();
-        case kRGB_565_SkColorType:
-        case kGray_8_SkColorType:
-            return kOpaque_SkAlphaType == src.alphaType() && !needs_color_xform(dst, src);
-        default:
-            return false;
-    }
-}
-
 #endif // SkCodecPriv_DEFINED