Remove unnecessary include and dependency in ui/latency/mojo

gn check --check-generated reported a missing build
dependency and this fixes that. An example of a reported error is:

ERROR at //out/Default/gen/ui/latency/mojo/latency_info.mojom-forward.h:44:11: Can't include this header from here.
          ^----------------------
The target:
  //ui/latency/mojo:interfaces
is including a file from the target:
  //ipc:ipc

Since the header isn't actually used, the simple fix is to remove it, though that revealed some
other code that was missing includes of their own.

Bug: 938893
Change-Id: I8e2648d5e681ee9640282eab31028a102cdc96eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1550467
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: kylechar <kylechar@chromium.org>
Commit-Queue: kylechar <kylechar@chromium.org>
Auto-Submit: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#653575}
3 files changed