Initial KTX file decoder

tests/ImageDecodingTest.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkColor.h"
@@ skipping 36 matching lines @@
     switch (format) {
         case SkImageDecoder::kPNG_Format:
         case SkImageDecoder::kWEBP_Format:
             return false;
         // Skip unknown since it will not be decoded anyway.
         case SkImageDecoder::kUnknown_Format:
         // Technically ICO and BMP supports alpha channels, but our image
         // decoders do not, so skip them as well.
         case SkImageDecoder::kICO_Format:
         case SkImageDecoder::kBMP_Format:
+        // KTX is a Texture format so it's not particularly clear how to 
+        // decode the alpha from it.
+        case SkImageDecoder::kKTX_Format:
         // The rest of these are opaque.
         case SkImageDecoder::kPKM_Format:
         case SkImageDecoder::kWBMP_Format:
         case SkImageDecoder::kGIF_Format:
         case SkImageDecoder::kJPEG_Format:
             return true;
     }
     SkASSERT(false);
     return true;
 }
@@ skipping 652 matching lines @@
                     }
                     SkDecodingImageGenerator::Options options(scaleList[i],
                                                               ditherList[j]);
                     test_options(reporter, options, encodedStream, encodedData,
                                  useDataList[m], path);
                 }
             }
         }
     }
 }