I've tried to use flattenhtml="true" in Audio Player and I got the following traceback, because grit mistook Polymer data binding.

ninja -C out/cOS chrome browser_tests nacl_helper -j 1120 -l 56
ninja: Entering directory `out/cOS'
[1/46] ACTION //ui/file_manager:resources_grit(//build/toolchain/linux:clang_x64)
FAILED: gen/ui/file_manager/resources_stamp.d.stamp gen/ui/file_manager/grit/file_manager_resources.h gen/ui/file_manager/grit/file_manager_resources_map.cc gen/ui/file_manager/grit/file_manager_resources_map.h gen/ui/file_manager/file_manager_resources.pak gen/ui/file_manager/file_manager_resources.rc gen/ui/file_manager/file_manager_resources.pak.info
python ../../tools/grit/grit.py -i ../../ui/file_manager/file_manager_resources.grd build -o gen/ui/file_manager --depdir . --depfile gen/ui/file_manager/resources_stamp.d --write-only-new=1 --depend-on-stamp -D _chromium -E CHROMIUM_BUILD=chromium -D chromeos -D scale_factors=2x -D toolkit_views -D use_aura -D use_nss_certs -D use_ozone -f ../../tools/gritsettings/resource_ids --assert-file-list=obj/ui/file_manager/resources_expected_outputs.txt
Error processing node <?xml version="1.0" encoding="UTF-8"?>
<include file="audio_player/elements/track_info_panel.html" flattenhtml="true" name="IDR_AUDIO_PLAYER_ELEMENTS_TRACK_INFO_PANEL_HTML" type="BINDATA" />
Traceback (most recent call last):
  File "../../tools/grit/grit.py", line 15, in <module>
    grit.grit_runner.Main(sys.argv[1:])
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/grit_runner.py", line 249, in Main
    toolobject.Run(options, args[1:])
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/tool/build.py", line 256, in Run
    self.Process()
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/tool/build.py", line 395, in Process
    self.ProcessNode(self.res, output, outfile)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/tool/build.py", line 320, in ProcessNode
    formatted = formatter(node, output_node.GetLanguage(), output_dir=base_dir)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/data_pack.py", line 83, in Format
    value = node.GetDataPackValue(lang, UTF8)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/node/include.py", line 85, in GetDataPackValue
    data = self._GetFlattenedData(allow_external_script=allow_external_script)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/node/include.py", line 40, in _GetFlattenedData
    allow_external_script=allow_external_script))
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 536, in InlineToString
    filename_expansion_function=filename_expansion_function).inlined_data
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 508, in DoInline
    flat_text = InlineCSSImages(flat_text)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 451, in InlineCSSImages
    text)
  File "/usr/lib/python2.7/re.py", line 155, in sub
    return _compile(pattern, flags).sub(repl, string, count)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 450, in <lambda>
    lambda m: InlineCSSUrls(m, filepath),
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 458, in InlineCSSUrls
    src_match.group(0))
  File "/usr/lib/python2.7/re.py", line 155, in sub
    return _compile(pattern, flags).sub(repl, string, count)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 457, in <lambda>
    lambda m: SrcReplace(m, filepath),
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 291, in SrcReplace
    filename_expansion_function=filename_expansion_function)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 156, in SrcInlineAsDataURL
    inlined_files, names_only)
  File "/usr/local/google/home/lucmult/chromium/src/tools/grit/grit/format/html_inline.py", line 125, in ConvertFileToDataURL
    'cannot be stored in a data url.' % filename)
Exception: [[track.artworkUrl]] is of an an unknown type and cannot be stored in a data url.
ninja: build stopped: subcommand failed.