Refactor sync_manager_impl.h to use NetworkChangeObserver

IPAddressObserver and ConnectionTypeObserver are deprecated. This CL
modifies SyncManagerImpl to use NetworkChangeObserver instead.

Note that when device is coming online, a CONNECTION_NONE will always
be sent before the actual connection type, so I modified
OnConnectionStatusChange to take into account the connection type before retry.

Bug: 754695
Change-Id: I25dd585a84f1c6736546e931f19596e9788b6c15
Reviewed-on: https://chromium-review.googlesource.com/677550
Reviewed-by: Pavel Yatsuk <[email protected]>
Commit-Queue: Helen Li <[email protected]>
Cr-Commit-Position: refs/heads/master@{#514278}
9 files changed