Fix bmp RLE "bug" and add invalid image test to CodexTest

src/codec/SkBmpRLECodec.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.
  */
 
 #include "SkBmpCodec.h"
 #include "SkColorTable.h"
 #include "SkImageInfo.h"
@@ skipping 38 matching lines @@
 
     /*
      * Creates the color table
      * Sets colorCount to the new color count if it is non-NULL
      */
     bool createColorTable(int* colorCount);
 
     bool initializeStreamBuffer();
 
     /*
+     * It is possible for an encoded image stream to contain more encoded data than
+     * it reports that it has.  Before signalling kIncompleteInput, we should check

[scroggo, 2015/08/12 14:14:30]

Maybe this should say something like:

Before signaling kIncompleteInput, we call this method to attempt to load the
stream buffer with any additional data.

[msarett, 2015/08/12 15:01:24]

Agreed.  Done.

+     * if we can reset the stream buffer with additional data.
+     *
+     * @return the number of bytes remaining in the new stream buffer

[scroggo, 2015/08/12 14:14:30]

nit: In my mind, the stream buffer itself is not new - just the data

[msarett, 2015/08/12 15:01:24]

Yeah agreed.  I need the remove the work "new" from all of my comments.

+     */
+    size_t resetStreamBuffer();

[scroggo, 2015/08/12 14:14:30]

I'm not a big fan of the name. It doesn't really explain its purpose. Maybe it
should be something like checkForMoreData?or checkForExtraData?

[msarett, 2015/08/12 15:01:24]

I like checkForMoreData.

+
+    /*
      * Set an RLE pixel using the color table
      */
     void setPixel(void* dst, size_t dstRowBytes,
                   const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
                   uint8_t index);
     /*
      * Set an RLE24 pixel from R, G, B values
      */
     void setRGBPixel(void* dst, size_t dstRowBytes,
                      const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
                      uint8_t red, uint8_t green, uint8_t blue);
 
     /*
      * Performs the bitmap decoding for RLE input format
      */
     Result decode(const SkImageInfo& dstInfo, void* dst,
                   size_t dstRowBytes, const Options& opts);
 
     SkAutoTUnref<SkColorTable>          fColorTable;    // owned
     const uint32_t                      fNumColors;
     const uint32_t                      fBytesPerColor;
     const uint32_t                      fOffset;
     SkAutoTDeleteArray<uint8_t>         fStreamBuffer;
     size_t                              fRLEBytes;
     uint32_t                            fCurrRLEByte;
 
     typedef SkBmpCodec INHERITED;
 };