Cleanup: Remove unnecessary forward declarations from some views files.

Cautch in
https://skia.googlesource.com/skia/+/a3a706fcd4cc9376a1223a53f57589f29d4a36ea

BUG=None
TEST=None
R=djsollen@google.com

Review URL: https://codereview.chromium.org/680253004
2 files changed