Switch SkAutoMalloc to SkAutoTMalloc to avoid cast

src/images/SkImageDecoder_libwebp.cpp

 /*
  * Copyright 2010, The Android Open Source Project
  *
  * 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
@@ skipping 183 matching lines @@
         WebPFreeDecBuffer(&config->output);
         return false;
     }
 
     if (!stream->rewind()) {
         SkDebugf("Failed to rewind webp stream!");
         return false;
     }
     const size_t readBufferSize = stream->hasLength() ?
             SkTMin(stream->getLength(), WEBP_IDECODE_BUFFER_SZ) : WEBP_IDECODE_BUFFER_SZ;
-    SkAutoMalloc srcStorage(readBufferSize);
-    unsigned char* input = (uint8_t*)srcStorage.get();
+    SkAutoTMalloc<unsigned char> srcStorage(readBufferSize);
+    unsigned char* input = srcStorage.get();
     if (nullptr == input) {
         WebPIDelete(idec);
         WebPFreeDecBuffer(&config->output);
         return false;
     }
 
     bool success = true;
     VP8StatusCode status = VP8_STATUS_SUSPENDED;
     do {
         const size_t bytesRead = stream->read(input, readBufferSize);
@@ skipping 334 matching lines @@
     return SkImageDecoder::kUnknown_Format;
 }
 
 static SkImageEncoder* sk_libwebp_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kWEBP_Type == t) ? new SkWEBPImageEncoder : nullptr;
 }
 
 static SkImageDecoder_DecodeReg gDReg(sk_libwebp_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_webp);
 static SkImageEncoder_EncodeReg gEReg(sk_libwebp_efactory);