Implement IpcFileOperations

Now that FileTransferMessageHandler has been migrated to the new
FileOperations interface, the next step is to enable proxying the
FileOperations interface over IPC, which is required for Windows support
due to the multi-process architecture we use there.

Bug: 679313
Change-Id: Ib6ed3c90abd8ddc4d84b23b78e3877dfb0048dd9
Reviewed-on: https://chromium-review.googlesource.com/c/1371220
Commit-Queue: Erik Jensen <rkjnsn@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Joe Downing <joedow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622575}
16 files changed