Web MIDI: distributes MIDIPort information asynchronously
MidiPortInfoList for input and output devices were accessible
from MidiHost, and MidiHost distributed it via IPC on sending
MidiMsg_SessionStarted. To update these device lists asynchronously
and keep them consistent in all renderers, stop exposing them
and invoke a client method, AddInputPort() or AddOutputPort() insteads.
These client methods are called for all existing devices on opening
a session at once.
If MidiManager supports, these can be called for a device on each
connection and disconnection.
BUG=422333
TEST=media_unittests
Review URL: https://codereview.chromium.org/664843002
Cr-Commit-Position: refs/heads/master@{#300894}
10 files changed
