Fill incomplete images in SkCodec parent class

src/codec/SkCodec_wbmp.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCodec_wbmp_DEFINED
 #define SkCodec_wbmp_DEFINED
 
 #include "SkCodec.h"
 #include "SkSwizzler.h"
 
 class SkWbmpCodec final : public SkCodec {
 public:
     static bool IsWbmp(SkStream*);
 
     /*
      * Assumes IsWbmp was called and returned true
      * Creates a wbmp codec
      * Takes ownership of the stream
      */
     static SkCodec* NewFromStream(SkStream*);
 
 protected:
     SkEncodedFormat onGetEncodedFormat() const override;
     Result onGetPixels(const SkImageInfo&, void*, size_t,
-                       const Options&, SkPMColor[], int*) override;
+                       const Options&, SkPMColor[], int*, int*) override;
     bool onRewind() override;
 private:
     /*
      * Returns a swizzler on success, nullptr on failure
      */
     SkSwizzler* initializeSwizzler(const SkImageInfo& info, const SkPMColor* ctable,
                                    const Options& opts);
-    SkSampler* getSampler() override { return fSwizzler; }
+    SkSampler* getSampler(bool createIfNecessary) override {
+        SkASSERT(fSwizzler || !createIfNecessary);
+        return fSwizzler;
+    }
 
     /*
      * Read a src row from the encoded stream
      */
-    Result readRow(uint8_t* row);
+    bool readRow(uint8_t* row);
 
     SkWbmpCodec(const SkImageInfo&, SkStream*);
 
-    const size_t fSrcRowBytes;
+    const size_t                 fSrcRowBytes;
 
     // Used for scanline decodes:
+    SkAutoTDelete<SkSwizzler>    fSwizzler;
     SkAutoTUnref<SkColorTable>   fColorTable;
-    SkAutoTDelete<SkSwizzler>    fSwizzler;
     SkAutoTMalloc<uint8_t>       fSrcBuffer;
 
     // FIXME: Override onSkipScanlines to avoid swizzling.
-    Result onGetScanlines(void* dst, int count, size_t dstRowBytes) override;
+    int onGetScanlines(void* dst, int count, size_t dstRowBytes) override;
     Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options,
             SkPMColor inputColorTable[], int* inputColorCount) override;
 
     typedef SkCodec INHERITED;
 };
 
 #endif  // SkCodec_wbmp_DEFINED