Fill incomplete images in SkCodec parent class

Rather than implementing some sort of "fill" in every
SkCodec subclass for incomplete images, let's make the
parent class handle this situation.

This includes an API change to SkCodec.h

SkCodec::getScanlines() now returns the number of lines it
read successfully, rather than an SkCodec::Result enum.
getScanlines() most often fails on an incomplete input, in
which case it is useful to know how many lines were
successfully decoded - this provides more information than
kIncomplete vs kSuccess.  We do lose information when the
API is used improperly, as we are no longer able to return
kInvalidParameter or kScanlineNotStarted.

Known Issues:
Does not work for incomplete fFrameIsSubset gifs.
Does not work for incomplete icos.

BUG=skia:

Review URL: https://codereview.chromium.org/1332053002

1 files changed, 4 insertions, 4 deletions

diff --git a/src/codec/SkBmpRLECodec.h b/src/codec/SkBmpRLECodec.h
index 8721969a85..fcf910d8e5 100644
--- a/src/codec/SkBmpRLECodec.h
+++ b/src/codec/SkBmpRLECodec.h
@@ -46,7 +46,7 @@ protected:
 
     Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
                        size_t dstRowBytes, const Options&, SkPMColor*,
-                       int*) override;
+                       int*, int*) override;
 
     SkCodec::Result prepareToDecode(const SkImageInfo& dstInfo,
             const SkCodec::Options& options, SkPMColor inputColorPtr[],
@@ -84,10 +84,10 @@ private:
                      const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
                      uint8_t red, uint8_t green, uint8_t blue);
 
-    Result decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
-                      const Options& opts) override;
+    int decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
+            const Options& opts) override;
 
-    SkSampler* getSampler() override;
+    SkSampler* getSampler(bool createIfNecessary) override;
 
     SkAutoTUnref<SkColorTable>          fColorTable;    // owned
     const uint32_t                      fNumColors;