Dr. Memory reports that net::FileStream::Context is leaking file handles:

https://build.chromium.org/p/chromium.memory.fyi/builders/Windows%20Content%20Browser%20%28DrMemory%20full%29%20%282%29/builds/3345

HANDLE LEAK: KERNEL handle 0x000002ec and 3 similar handle(s) were opened but not closed:
# 0 system call NtCreateFile
# 1 KERNELBASE.dll!CreateFileW                                           +0x35d    (0x7673c5fd <KERNELBASE.dll+0x1c5fd>)
# 2 KERNEL32.dll!CreateFileW                                             +0x49     (0x76cb3f56 <KERNEL32.dll+0x13f56>)
# 3 base.dll!base::File::DoInitialize                                     [base\files\file_win.cc:383]
# 4 base.dll!base::File::Initialize                                       [base\files\file.cc:93]
# 5 net.dll!net::FileStream::Context::OpenFileImpl                        [net\base\file_stream_context.cc:167]
# 6 net.dll!base::internal::Invoker<>::Run                                [base\bind_internal.h:352]
# 7 net.dll!base::internal::ReturnAsParamAdapter<>                        [base\task_runner_util.h:23]
# 8 net.dll!base::internal::Invoker<>::Run                                [base\bind_internal.h:352]
# 9 base.dll!base::`anonymous namespace'::PostTaskAndReplyRelay::Run      [base\threading\post_task_and_reply_impl.cc:43]
#10 base.dll!base::SequencedWorkerPool::Inner::ThreadLoop                 [base\threading\sequenced_worker_pool.cc:834]
#11 base.dll!base::SequencedWorkerPool::Worker::Run                       [base\threading\sequenced_worker_pool.cc:535]
#12 base.dll!base::SimpleThread::ThreadMain                               [base\threading\simple_thread.cc:66]
#13 base.dll!base::`anonymous namespace'::ThreadFunc                      [base\threading\platform_thread_win.cc:84]
#14 KERNEL32.dll!BaseThreadInitThunk                                     +0x11     (0x76cb337a <KERNEL32.dll+0x1337a>)
Note: @0:03:05.593 in thread 1576
Note: handles created with the same callstack are closed here:
Note: # 0 system call NtClose
Note: # 1 KERNELBASE.dll!CloseHandle                                      +0x2c     (0x7672c463 <KERNELBASE.dll+0xc463>)
Note: # 2 KERNEL32.dll!CloseHandle                                        +0x27     (0x76cb1418 <KERNEL32.dll+0x11418>)
Note: # 3 base.dll!`anonymous namespace'::CloseHandleWrapper               [base\win\scoped_handle.cc:116]
Note: # 4 base.dll!`anonymous namespace'::ActiveVerifier::CloseHandle      [base\win\scoped_handle.cc:178]
Note: # 5 base.dll!base::win::HandleTraits::CloseHandle                    [base\win\scoped_handle.cc:264]
Note: # 6 base.dll!base::File::Close                                       [base\files\file_win.cc:40]
Note: # 7 net.dll!net::FileStream::Context::CloseFileImpl                  [net\base\file_stream_context.cc:179]
Note: # 8 net.dll!base::internal::Invoker<>::Run                           [base\bind_internal.h:352]
Note: # 9 base.dll!base::SequencedWorkerPool::Inner::ThreadLoop            [base\threading\sequenced_worker_pool.cc:834]
Note: #10 base.dll!base::SequencedWorkerPool::Worker::Run                  [base\threading\sequenced_worker_pool.cc:535]
Note: #11 base.dll!base::SimpleThread::ThreadMain                          [base\threading\simple_thread.cc:66]
Note: #12 base.dll!base::`anonymous namespace'::ThreadFunc                 [base\threading\platform_thread_win.cc:84]
Note: #13 KERNEL32.dll!BaseThreadInitThunk                                +0x11     (0x76cb337a <KERNEL32.dll+0x1337a>)
The report came from the `MediaSourceTest.Playback_VideoOnly_WebM` test.

Unfortunately that stack doesn't give much information about which file handle was leaked.