Modify SkPngCodec to recognize 565 images from the sBIT chunk

src/codec/SkPngCodec.cpp

 /*
  * Copyright 2015 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 "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 688 matching lines @@
             color = SkEncodedInfo::kRGBA_Color;
             alpha = SkEncodedInfo::kUnpremul_Alpha;
             break;
         default:
             // All the color types have been covered above.
             SkASSERT(false);
             color = SkEncodedInfo::kRGBA_Color;
             alpha = SkEncodedInfo::kUnpremul_Alpha;
     }
 
+    // Add a special check for 565.
+    if (SkEncodedInfo::kOpaque_Alpha == alpha) {
+        png_color_8p sigBits;
+        if (png_get_sBIT(png_ptr, info_ptr, &sigBits)) {
+            if (5 == sigBits->red && 6 == sigBits->green && 5 == sigBits->blue) {
+                color = SkEncodedInfo::k565_Color;
+            }
+        }
+    }
+
     int numberPasses = png_set_interlace_handling(png_ptr);
 
     autoClean.release();
     if (png_ptrp) {
         *png_ptrp = png_ptr;
     }
     if (info_ptrp) {
         *info_ptrp = info_ptr;
     }
 
@@ skipping 160 matching lines @@
     SkCodec* outCodec;
     if (read_header(stream, chunkReader, &outCodec, nullptr, nullptr)) {
         // Codec has taken ownership of the stream.
         SkASSERT(outCodec);
         streamDeleter.release();
         return outCodec;
     }
 
     return nullptr;
 }