Fix thumbnail store crashing on loading old files

third_party/android_opengl/etc1/etc1.h

 // Copyright 2009 Google Inc.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 17 matching lines @@
 // pIn - pointer to the image data. Formatted such that
 //       pixel (x,y) is at pIn + pixelSize * x + stride * y;
 // pOut - pointer to encoded data. Must be large enough to store entire encoded image.
 // pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image.
 // returns non-zero if there is an error.
 
 bool etc1_encode_image(const unsigned char* pIn, unsigned int width, unsigned int height,
          unsigned int pixelSize, unsigned int stride, unsigned char* pOut, unsigned int outWidth,
          unsigned int outHeight);
 
+// Size of a PKM header, in bytes.
+
+#define ETC_PKM_HEADER_SIZE 16
+
+// Format a PKM header
+
+void etc1_pkm_format_header(unsigned char* pHeader, unsigned int width, unsigned int height);
+
+// Check if a PKM header is correctly formatted.
+
+bool etc1_pkm_is_valid(const unsigned char* pHeader);
+
+// Read the image width from a PKM header
+
+unsigned int etc1_pkm_get_width(const unsigned char* pHeader);
+
+// Read the image height from a PKM header
+
+unsigned int etc1_pkm_get_height(const unsigned char* pHeader);
+
 #endif // THIRD_PARTY_ANDROID_OPENGL_ETC1_ETC1_H_