RemoteMacViews: Move tooltip manager to browser side

Move TooltipManager from BridgedNativeWidget (in the app shim side)
to BridgedNativeWidgetHost (in the browser side). Change the one
method in TooltipManagerMac that interacted with Cocoa to go through
mojo instead.

This is necessary to ensure that NativeWidgetMac::GetTooltipManager
works when NativeWidgetMac (in the browser) does not have direct
access to BridgedNativeWidgetImpl (in the app shim).

Bug: 859152
Change-Id: I46ceeeed8e18f3fab35ace5664bb17ceff5da40c
Reviewed-on: https://chromium-review.googlesource.com/1205496
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: ccameron <ccameron@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589260}
8 files changed