The Google C++ style guide says that when both use a declaration, both
the .h file and the .cc file should include the relevant header.
Bug: webrtc:12057
Change-Id: I4c01ce8930d73418cb23c7fe1bb7bcd12c1e2568
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/189541
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32435}