Android: Remove build_tools_version

Now that we use Android Studio's sdk, we are no longer tied to the build
tools version in third_party/android_tools. This way Android Studio no
longer needs to warn about obsolete build_tools_version every sync.

Bug: 620034
Change-Id: I4e7f2c68694b650ab96219c53563007670312ba8
Reviewed-on: https://chromium-review.googlesource.com/c/1375633
Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616326}
2 files changed