AW: split utility/ into separate build file

No change to source code, this just splits up the top-level
android_webview build target, moving utility/* files under a new
utility/BUILD.gn file.

This aligns with Chrome's layout, which //chrome/utility/BUILD.gn.

Bug: 934152
Test: gn check out/Default/ //android_webview/utility
Change-Id: I0f573ab8bde4cae559fe86f92bf173d0c3679d57
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1533178
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642983}
2 files changed