Revert of Fix colorType/alphaType checks in SkCodec (patchset #5 id:80001 of https://codereview.chromium.org/1695473002/ )

Reason for revert:
Really bad images in Gold.

Original issue's description:
> Fix colorType/alphaType checks in SkCodec
>
> Make getPixels() and startScanlineDecode() behave
> consistently.
>
> Require that kGray8 decodes are opaque.
>
> Assert that creating the swizzler succeeds.
>
> BUG=skia:4203
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1695473002
>
> Committed: https://skia.googlesource.com/skia/+/c7578b6cdd03b61f076ffc7956efd952d6c301c0

TBR=scroggo@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:4203

Review URL: https://codereview.chromium.org/1694023002

1 files changed, 18 insertions, 19 deletions

diff --git a/src/codec/SkWbmpCodec.cpp b/src/codec/SkWbmpCodec.cpp
index 706d5ddd46..af1ab46f73 100644
--- a/src/codec/SkWbmpCodec.cpp
+++ b/src/codec/SkWbmpCodec.cpp
@@ -30,19 +30,6 @@ static inline void setup_color_table(SkColorType colorType,
     }
 }
 
-static inline bool valid_color_type(SkColorType colorType, SkAlphaType alphaType) {
-    switch (colorType) {
-        case kN32_SkColorType:
-        case kIndex_8_SkColorType:
-            return true;
-        case kGray_8_SkColorType:
-        case kRGB_565_SkColorType:
-            return kOpaque_SkAlphaType == alphaType;
-        default:
-            return false;
-    }
-}
-
 static bool read_byte(SkStream* stream, uint8_t* data)
 {
     return stream->read(data, 1) == 1;
@@ -97,6 +84,16 @@ bool SkWbmpCodec::onRewind() {
 
 SkSwizzler* SkWbmpCodec::initializeSwizzler(const SkImageInfo& info, const SkPMColor* ctable,
         const Options& opts) {
+    // Create the swizzler based on the desired color type
+    switch (info.colorType()) {
+        case kIndex_8_SkColorType:
+        case kN32_SkColorType:
+        case kRGB_565_SkColorType:
+        case kGray_8_SkColorType:
+            break;
+        default:
+            return nullptr;
+    }
     return SkSwizzler::CreateSwizzler(SkSwizzler::kBit, ctable, info, opts);
 }
 
@@ -127,8 +124,7 @@ SkCodec::Result SkWbmpCodec::onGetPixels(const SkImageInfo& info,
         return kUnimplemented;
     }
 
-    if (!valid_color_type(info.colorType(), info.alphaType()) ||
-            !valid_alpha(info.alphaType(), this->getInfo().alphaType())) {
+    if (!valid_alpha(info.alphaType(), this->getInfo().alphaType())) {
         return kInvalidConversion;
     }
 
@@ -137,7 +133,9 @@ SkCodec::Result SkWbmpCodec::onGetPixels(const SkImageInfo& info,
 
     // Initialize the swizzler
     SkAutoTDelete<SkSwizzler> swizzler(this->initializeSwizzler(info, ctable, options));
-    SkASSERT(swizzler);
+    if (nullptr == swizzler.get()) {
+        return kInvalidConversion;
+    }
 
     // Perform the decode
     SkISize size = info.dimensions();
@@ -195,8 +193,7 @@ SkCodec::Result SkWbmpCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
         return kUnimplemented;
     }
 
-    if (!valid_color_type(dstInfo.colorType(), dstInfo.alphaType()) ||
-            !valid_alpha(dstInfo.alphaType(), this->getInfo().alphaType())) {
+    if (!valid_alpha(dstInfo.alphaType(), this->getInfo().alphaType())) {
         return kInvalidConversion;
     }
 
@@ -210,7 +207,9 @@ SkCodec::Result SkWbmpCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
 
     // Initialize the swizzler
     fSwizzler.reset(this->initializeSwizzler(dstInfo, get_color_ptr(fColorTable.get()), options));
-    SkASSERT(fSwizzler);
+    if (nullptr == fSwizzler.get()) {
+        return kInvalidConversion;
+    }
 
     fSrcBuffer.reset(fSrcRowBytes);