Revert of replace kIgnore_SkAlphaType with kUnknown_SkAlphaType

src/utils/mac/SkCreateCGImageRef.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkCGUtils.h"
 #include "SkBitmap.h"
 #include "SkColorPriv.h"
 
 static CGBitmapInfo ComputeCGAlphaInfo_RGBA(SkAlphaType at) {
     CGBitmapInfo info = kCGBitmapByteOrder32Big;
     switch (at) {
-        case kUnknown_SkAlphaType:
-            break;
         case kOpaque_SkAlphaType:
+        case kIgnore_SkAlphaType:
             info |= kCGImageAlphaNoneSkipLast;
             break;
         case kPremul_SkAlphaType:
             info |= kCGImageAlphaPremultipliedLast;
             break;
         case kUnpremul_SkAlphaType:
             info |= kCGImageAlphaLast;
             break;
     }
     return info;
 }
 
 static CGBitmapInfo ComputeCGAlphaInfo_BGRA(SkAlphaType at) {
     CGBitmapInfo info = kCGBitmapByteOrder32Little;
     switch (at) {
-        case kUnknown_SkAlphaType:
-            break;
         case kOpaque_SkAlphaType:
+        case kIgnore_SkAlphaType:
             info |= kCGImageAlphaNoneSkipFirst;
             break;
         case kPremul_SkAlphaType:
             info |= kCGImageAlphaPremultipliedFirst;
             break;
         case kUnpremul_SkAlphaType:
             info |= kCGImageAlphaFirst;
             break;
     }
     return info;
@@ skipping 253 matching lines @@
         default:
             // we don't know if we're opaque or not, so compute it.
             if (SkBitmap::ComputeIsOpaque(tmp)) {
                 tmp.setAlphaType(kOpaque_SkAlphaType);
             }
     }
 
     *dst = tmp;
     return true;
 }