Update third_party/android_sdk/public/ emulator, platforms and sources packages

Update platforms to android-28 according to gn file https://cs.chromium.org/chromium/src/build/config/android/config.gni?sq=package:chromium&q=config.gn&g=0&l=91
Also update emulator and sources packages by convenience.

Bug: 659808
Change-Id: I4892f8c0099400fbd8099525ead4edc134215349
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1510074
Commit-Queue: Yun Liu <yliuyliu@google.com>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#639138}
8 files changed