Android: Use default sdk dir for Android Studio

Rather than use `third_party/android_tools/sdk` and
`third_party/android_ndk`, create and use the default `~/Android/Sdk`
directory instead for Android Studio. This allows a consistent dev
environment that does not change per-repository and also allows frequent
updates without affecting each checkout.

Necessary for native support and emulators. This will become the default
in the near future. For now, use:

build/android/gradle/generate_gradle.py --sdk AndroidStudioDefault

Bug: 840542,620034
Change-Id: Ia482cb2982472410fe9c515c5f5f9856f3eadfaf
Reviewed-on: https://chromium-review.googlesource.com/1058308
Commit-Queue: Peter Wen <wnwen@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559166}
2 files changed