Add session ID to VpnTransportInfo

- This will be visible only to apps with the NETWORK_SETTINGS
  permissions (signature), and will be redacted for all other callers.
- This string is expected to be the same as set by
  VpnService#setSession, and in general, VpnConfig.session. But it
  will be a general API that Vpn.java can call when setting the
  VpnTransportInfo.
- This string cannot be updated once the VPN NetworkAgent is connected.

Bug: 171872481
Ignore-AOSP-First: needed to prevent automerger race breaking build
Test: atest ConnectivityServiceTest
      atest VpnTransportInfoTest
      atest NetworkAgentTest
Change-Id: I883035262465238c35c5a931d89707f3e84feef8
1 file changed
tree: 108a0333fa4feb1d360fac40b593c0c3df62fe6b
  1. tests/
  2. Tethering/
  3. .gitignore
  4. OWNERS
  5. PREUPLOAD.cfg
  6. TEST_MAPPING