Navigation: Convert BeginNavigation to a mojo method

- Replace the old BeginNavigation IPC by the equivalent mojo call in
the FrameHost interface. Removed all reference to the old IPC and the
render_frame_host callback.

- Convert BeginNavigationParams to a mojo structure. Most of this patch
is simply modifying function prototypes to match the new mojo syntax.

Bug: 784904
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_site_isolation
Change-Id: I6f288c1d44c6dd7ab34726689ebf241ae45f73de
Reviewed-on: https://chromium-review.googlesource.com/763529
Reviewed-by: Daniel Cheng <[email protected]>
Reviewed-by: Camille Lamy <[email protected]>
Commit-Queue: Arthur Hemery <[email protected]>
Cr-Commit-Position: refs/heads/master@{#520943}
32 files changed