GitLab

To support synchronous compositor for Android webview over mojo add
a struct trait for ScrollOffset

BUG=722928
TBR=vollick@chromium.org

Change-Id: I4138ac3ff93fc17e6a123335ac3a82975df48db4
Reviewed-on: https://chromium-review.googlesource.com/830115
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524713}