It appears that dlopen() doesn't work from packages just yet.

dlopen("libosmesa.so") fails with ZX_ERR_NOT_FOUND:
[3:364727959:0227/233158.953765:977193023:ERROR:gl_implementation.cc(292)] Failed to load libosmesa.so: Error loading shared library libosmesa.so: ZX_ERR_NOT_FOUND
[3:364727959:0227/233158.953866:977193122:FATAL:gl_surface_test_support.cc(81)] Check failed: init::InitializeGLOneOffImplementation( impl, fallback_to_software_gl, gpu_service_logging, disable_gl_drawing, init_extensions).
#00: StackTrace at ../../base/debug/stack_trace_fuchsia.cc:174
#01: std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) at ../../buildtools/third_party/libc++/trunk/include/ostream:1001
      (inlined by) std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(std::__1::basic_ostream<char, std::__1::char_traits<char> >& (*)(std::__1::basic_ostream<char, std::__1::char_traits<char> >&)) at ../../buildtools/third_party/libc++/trunk/include/ostream:195
      (inlined by) ~LogMessage at ../../base/logging.cc:582
#02: ~__vector_base at ../../buildtools/third_party/libc++/trunk/include/vector:439
      (inlined by) gl::(anonymous namespace)::InitializeOneOffHelper(bool) at ../../ui/gl/test/gl_surface_test_support.cc:82
#03: content::ContentTestSuite::Initialize() at ../../content/test/content_test_suite.cc:90
#04: base::TestSuite::Run() at ../../base/test/test_suite.cc:261
#05: base::RepeatingCallback<int ()>::Run() const & at ../../base/callback.h:124
      (inlined by) base::(anonymous namespace)::LaunchUnitTestsInternal(base::RepeatingCallback<int ()> const&, unsigned long, int, bool, base::RepeatingCallback<void ()> const&) at ../../base/test/launcher/unit_test_launcher.cc:225
#06: base::LaunchUnitTests(int, char**, base::RepeatingCallback<int ()> const&) at ../../base/test/launcher/unit_test_launcher.cc:576
#07: main at ../../content/test/run_all_unittests.cc:20
#08: pc 0x551a047bd3ae (libc.so,0x133ae)


I confirmed that the library exists by walking through /pkg via FileEnumerator (aka readdir):

[3:364727959:0227/233158.950844:977190103:ERROR:gl_implementation_osmesa.cc(37)] Contents of pkg:
[3:364727959:0227/233158.953182:977192438:ERROR:gl_implementation_osmesa.cc(46)] /pkg/lib/libosmesa.so


I have tried loading other variants of the path, including "/pkg/lib/libosmesa.so", and "lib/libosmesa.so". Nothing works. It might be an issue in Chrome or it might be in Fuchsia.