Stop calling jpeg_finish_decompress()

jpeg_finish_decompress() does several things:
(1) Reads to the end of the image stream.
(2) Calls term_src(), a client provided function that
indicates we are done with the memory stream.  Our current
implementation of term_src() does nothing.
(3) Calls jpeg_abort() which aborts the decode and cleans
up some memory.

I don't think we need to call this anymore.

(1) seems irrelevant.

It seems a little dangerous to get rid of (2), but it is
fine while our implementation of term_src() does nothing.

(3) We will call jpeg_destroy() on destruction of the
JpegDecoderManager.  This should free all the memory,
making it unnecessary to call jpeg_abort() beforehand.

BUG=skia:4040

Review URL: https://codereview.chromium.org/1370323004

3 files changed, 6 insertions, 23 deletions

diff --git a/src/codec/SkJpegCodec.cpp b/src/codec/SkJpegCodec.cpp
index c9dee9a663..30c1a39f06 100644
--- a/src/codec/SkJpegCodec.cpp
+++ b/src/codec/SkJpegCodec.cpp
@@ -373,11 +373,6 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
             SkSwizzler::Fill(dstRow, dstInfo, dstRowBytes, dstHeight - y,
                     SK_ColorBLACK, nullptr, options.fZeroInitialized);
 
-            // Prevent libjpeg from failing on incomplete decode
-            dinfo->output_scanline = dstHeight;
-
-            // Finish the decode and indicate that the input was incomplete.
-            jpeg_finish_decompress(dinfo);
             return fDecoderMgr->returnFailure("Incomplete image data", kIncompleteInput);
         }
 
@@ -389,7 +384,6 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
         // Move to the next row
         dstRow = SkTAddOffset<JSAMPLE>(dstRow, dstRowBytes);
     }
-    jpeg_finish_decompress(dinfo);
 
     return kSuccess;
 }
@@ -458,20 +452,6 @@ SkCodec::Result SkJpegCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
     return kSuccess;
 }
 
-SkJpegCodec::~SkJpegCodec() {
-    // FIXME: This probably does not need to be called after a full decode
-    // FIXME: Is it safe to call when it doesn't need to be called?
-    if (setjmp(fDecoderMgr->getJmpBuf())) {
-        SkCodecPrintf("setjmp: Error in libjpeg finish_decompress\n");
-        return;
-    }
-
-    // We may not have decoded the entire image.  Prevent libjpeg-turbo from failing on a
-    // partial decode.
-    fDecoderMgr->dinfo()->output_scanline = this->getInfo().height();
-    jpeg_finish_decompress(fDecoderMgr->dinfo());
-}
-
 SkCodec::Result SkJpegCodec::onGetScanlines(void* dst, int count, size_t rowBytes) {
     // Set the jump location for libjpeg errors
     if (setjmp(fDecoderMgr->getJmpBuf())) {
diff --git a/src/codec/SkJpegCodec.h b/src/codec/SkJpegCodec.h
index 24594c1226..6377c9d469 100644
--- a/src/codec/SkJpegCodec.h
+++ b/src/codec/SkJpegCodec.h
@@ -95,8 +95,6 @@ private:
      */
     SkJpegCodec(const SkImageInfo& srcInfo, SkStream* stream, JpegDecoderMgr* decoderMgr);
 
-    ~SkJpegCodec() override;
-
     /*
      * Checks if the conversion between the input image and the requested output
      * image has been implemented
diff --git a/src/codec/SkJpegUtility_codec.cpp b/src/codec/SkJpegUtility_codec.cpp
index 75a562a004..19ece5e6ad 100644
--- a/src/codec/SkJpegUtility_codec.cpp
+++ b/src/codec/SkJpegUtility_codec.cpp
@@ -61,7 +61,12 @@ static void sk_skip_input_data(j_decompress_ptr dinfo, long numBytes) {
  * We do not need to do anything to terminate our stream
  */
 static void sk_term_source(j_decompress_ptr dinfo)
-{}
+{
+    // The current implementation of SkJpegCodec does not call
+    // jpeg_finish_decompress(), so this function is never called.
+    // If we want to modify this function to do something, we also
+    // need to modify SkJpegCodec to call jpeg_finish_decompress().
+}
 
 /*
  * Constructor for the source manager that we provide to libjpeg