Merge changes from topic 'skia_merge'

* changes:
  Fix include to match Skia filename change
  Remove references to SkImageDecoder (part 2)
  Update SkiaCanvasProxy with SkSurface API change
  Return DNG mimeType for the case kDNG_SkEncodedFormat
  Remove use of SkFixed. Update code to use SkGlyph.fAdvance[XY] after https://codereview.chromium.org/1737693006.
  skia SkDocument - new MakePDF API, fix leak