Revert of Fix colorType/alphaType checks in SkCodec

src/codec/SkBmpMaskCodec.cpp

Index: src/codec/SkBmpMaskCodec.cpp
diff --git a/src/codec/SkBmpMaskCodec.cpp b/src/codec/SkBmpMaskCodec.cpp
index 03c16c058896649ae5e9117736e432d6b85208a9..b173317c10a53ef9bee10721978e2b403080ad11 100644
--- a/src/codec/SkBmpMaskCodec.cpp
+++ b/src/codec/SkBmpMaskCodec.cpp
@@ -58,12 +58,25 @@
     return kSuccess;
 }
 
+bool SkBmpMaskCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& options) {
+    // Create the swizzler
+    fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(dstInfo, this->getInfo(), fMasks,
+            this->bitsPerPixel(), options));
+
+    if (nullptr == fMaskSwizzler.get()) {
+        return false;
+    }
+
+    return true;
+}
+
 SkCodec::Result SkBmpMaskCodec::prepareToDecode(const SkImageInfo& dstInfo,
         const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
-    // Initialize the mask swizzler
-    fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(dstInfo, this->getInfo(), fMasks,
-            this->bitsPerPixel(), options));
-    SkASSERT(fMaskSwizzler);
+    // Initialize a the mask swizzler
+    if (!this->initializeSwizzler(dstInfo, options)) {
+        SkCodecPrintf("Error: cannot initialize swizzler.\n");
+        return SkCodec::kInvalidConversion;
+    }
 
     return SkCodec::kSuccess;
 }