device/bluetooth:Implement BluetoothMediaEndpointServiceProvider delegate and media-related overrides.
This CL implements delegate overrides for
BluetoothMediaEndpointServiceProvider and observer overrides for
BluetoothMediaClient and BluetoothMediaTransportClient. These
overrides will be called once a remote device connects to a local
A2DP audio sink, and the state of the audio sink should become idle.
The behaviors of FakeBluetoothMediaTransportClient,
FakeBluetoothMediaEndpointServiceProvider and
FakeMediaEndpointServiceProvider are also defined for
connection-related tests in this CL.
BUG=441581
TEST=device_unittests --gtest_filter=*AudioSink*
Review URL: https://codereview.chromium.org/
910023002
Cr-Commit-Position: refs/heads/master@{#316709}