[mojo] include mojo header in /chrome/browser/media/cast_mirroring_service_host_browsertest.cc

This is preparation CL to use forward declaration only header in mojo's
generated code.
If we include forward declaration only header in mojo's generated code, we need
to include mojo header files in some places where definition is necessary.

master CL is in
https://chromium-review.googlesource.com/c/chromium/src/+/1438975

CC=​rockot@google.com

This CL was uploaded by git cl split.

TBR=miu@chromium.org

Bug: 922875
Change-Id: I58ed03aee02be6276e68c65fe7ad8eab5d9f4cc6
Reviewed-on: https://chromium-review.googlesource.com/c/1447157
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#627816}
1 file changed