Add a NetworkAgent API to indicate that a network will be replaced.

This is useful for link layers that disconnect but know they will
reconnect to a similar network soon, and do not want the device
to switch to another network until the reconnect happens. An
example is wifi switching to another network that is on a
different subnet without the device switching to cellular data.

This works by immediately destroying the network, so the link
layer can reuse the same interface name for the new network. It
would be possible to delay destroying the network until the new
network connects, but in practice this does not seem useful,
because the if the link layer reuses the interface, then the
interface will be undergoing reconfiguration, and will likely
not be usable for app traffic.

This CL also moves the call to onNetworkDestroyed into
destroyNativeNetwork. This is needed to ensure that the new
API calls onNetworkDestroyed even though most teardown
operations have not happened. This causes onNetworkDestroyed to
happen before the netId is marked free, but that shouldn't cause
any behavioural changes because netId allocation is an
implementation detail of ConnectivityService and is not
observable by apps or system components.

Bug: 216567577
Test: builds, boots
Test: atest FrameworksNetTests FrameworksNetIntegrationTests
Test: atest CtsNetTestCases:android.net.cts.ConnectivityManagerTest
Test: atest CtsNetTestCases:android.net.cts.NetworkAgentTest#testDestroyAndAwaitReplacement
Change-Id: I9f9e022fef66b31a29cce560413321075e992756

0 files changed, 0 insertions, 0 deletions